Download Elements, Compounds and Mixtures Elements are the simplest type

Elements, Compounds and Mixtures
Elements are the simplest type of substance.
An element contains only ONE type of atom.
A compound is a substance with 2 or more elements chemically joined together.
Mixtures are where 2 or more substances are present but are not chemically joined. These
can be easily separated by filtration, distillation, evaporation or chromatography (separates
colours).
A solution is made when a solid (solute) is dissolved in a liquid (solvent). Dilute
solution = lots of solvent : little solute.
Concentrated solution = little solvent : lots of solute
Saturated solution = no more solute can be dissolved in the solvent. A little more can be
dissolved on heating though.
Identifying Chemical Changes
A new substance is always formed in a chemical reaction. This can be identified by:
Change of appearance
Gas forming
Solid forming (precipitation)
Energy (temperature) change
Physical change may include some of these but does not form a new substance so can
be reversed. Physical changes include freezing, melting, boiling, making a solution.
Reaction Rates
Reaction rates can be increased by increasing the number of collisions by:
1.
2.
3.
4.
Increasing the temperature of the reactants.
Increasing the concentration of the reactants.
Increasing the surface area by decreasing particle size.
Adding a catalyst (which does not get used up)
Calculating Rate = change in quantity (of reactants of products)/change in time
Normamly seen as a change in volume, mass or concentration over aperiod of time in minutes
or secondsIt is important to remember the apparatus required for these types of experiments.
Gas can be collected by downward displacement or by a gas syringe. Mass can be measured if
the beaker is place on a balance and the gas product is allowed to escape.
If it is a simple reaction where one time is taken for the reaction to be complete then rate is
calculated as 1/time and normally calculated as per second. Units are s -1
Catalysts are very important in industry:
Catalytic converters use platinum and rhodium to convert poisonous gases into harmless
ones in car engines, iron helps makes ammonia for fertilisers, nickel helps turn oil into
margarine, the enzyme invertase turns hard sucrose into soft glucose and fructose in
sweets, zymase (in yeast) turns glucose into ethanol (alcohol). Enzymes are biological
catalysts.
Atom
The atom is made up of 3 sub-atomic particles:
Particle
Proton
Neutron
Electron
Charge
+1
0
-1
Mass (amu)
1
1
0 (almost)
Where found
Nucleus
Nucleus
Energy levels
Elements are listed in the Periodic Table in order of their Atomic Number.
Atomic number = number of protons.
Mass number = number of protons + number of neutrons. Number of electrons =
number of protons - charge.
Nuclide Notation
A simple way to show the mass and atomic number and any charge the Ion
has.
i.e
35
Cl
17
Electron Arrangement
The electrons occupy energy levels, or electron shells. These shells don't all take
the same number of electrons.
Shell
1
2
3
No. of
electrons
2
8
8
These shells are filled until all the electrons are placed, giving the electron
arrangement of the atom
Eg, Sodium has 11 electrons so has an electron arrangement of 2,8,1.
.Same group of the Periodic Table have the same number of electrons in their outer
electron shell. This gives them similar chemical properties.
Isotopes
These are atoms of the same element with different mass numbers. This
means they have the same atomic number but different mass numbers.
Relative Atomic Mass
This is the average mass of the mass numbers of a sample of an element,
including all its isotopes.
For example, a sample of chlorine has an average atomic mass of 35.5 amu. It has 2
isotopes. 75% of the sample have mass of 35amu while 25% have a mass of 37.
Calculation: Ave. mass = [(75 x 35) + (25 x 37)]/100
As the average is closer to 35, there must be more isotopes of mass 35 in the sample!
In the Periodic Table, the rows are known as periods while the columns are known as groups.
All elements are found in the Periodic Table in periods (rows) and groups (columns).
Elements in the same group have similar chemical properties due to having the
same number of outer electrons.
Group 1 - alkali metals - very reactive (lithium, sodium, etc.) Group 7 - halogens
- very reactive (fluorine, chlorine, etc.)
Group 8 or 0 - Noble gases - completely unreactive (helium, argon, etc.)
Bonding, Structure and Properties
Covalent Bonding
This occurs between 2 non-metal atoms.
2 electrons are shared between the 2 atoms and are held in place by the mutual
attraction of BOTH positive nuclei to EACH of the electrons (which have a negative
charge).
In Molecular Elements
There are 8 diatomic elements (2 atoms held by covalent bonding): Hydrogen (H 2),
Oxygen (02), Nitrogen (N2) and all of the Group 7 elements (Halogens).
In molecular compounds
When non-metal atoms join! Eg. Water (H20), ammonia (NH 3), Methane (CH 4) or the
diatomic elements. These have specific shapes because of the covalent bonds.
Covalent molecular substances tend to have low melting and boiling points because they only
have Van der Waals' forces holding the molecules together. Van der Waals' forces
increase with increasing size.
Covalent network substances (carbon in the form of diamond and graphite, silicon dioxide,
silicon carbide) have high melting and boiling points because all the atoms are
interlinked by strong covalent bonds which take a lot of energy to break.
Ionic Bonding
This forms between metals and non-metal. The metal loses its outer electrons becoming a
positive ion.
The non-metal takes these electrons to form a negative ion.
In both cases the ion ends up with a full outer electron shell, like the Noble gases.
The electrostatic force of attraction holds these oppositely charged ions together very
tightly. This is why ionic compounds tend to have high melting and boiling points. The
structure is a large lattice.
Metallic Bonding
Found in metal elements. The atoms lose their outer electrons which are then free to
move from one metal ion to the next. This free movement of electrons is why metals
conduct electricity.
Solubility
LIKE DISSOLVES LIKE
Ionic compounds dissolve in polar solvents, like water.
Covalent compounds (like candle wax) dissolve in covalent solvents (like hexane).
Electrical Conductivity
Metals conduct when solid or liquid.
Covalent compounds don't conduct at all.
Ionic compounds only conduct when molten (liquid) or in solution because the ions are
then free to move.
Electrical conductivity
Type of
Melting/boiling points
bonding
Solid
Liquid
Aqueous
Metallic
yes
yes
insoluble
High
Ionic
no
yes
yes
High
Covalent
molecules
no
no
no
Low
Covalent
network
no
no
no
High
Nuclear Chemistry
There are 3 types of radiation, alpha ( ), beta ( ) and gamma ( ). Their
properties can be studied using an electrical field.
Alpha particles
Alpha particles come from the nucleus of a radioactive atom. They consist of 2 protons and 2
neutrons; hence have a 2+ charge. A few centimeters of air will stop them.
Alpha radiation consists of helium nuclei,
Beta particles
A beta particle is an electron,
.
It is thought that a beta particle is formed when a neutron splits up into a proton and an electron.
While it will pass through air, it cannot penetrate thin metal foil.
Gamma waves
Gamma waves come from the nucleus of a radioactive atom. They are electronegative waves.
They do not change the nature of an atom.
Thick lead or concrete will absorb gamma rays
The 3 types of radiation behave quite differently when passes between electrically charged
plates.
Beta (β) rays are small and
negatively charged so they deflect
sharply towards the positive
+
Gamma (γ) radiation has
no mass and no charge so
passes straight through.
Alpha (α) particles are heavy and
positively charged and bend slightly
towards the negative
-
Nuclear equations show the products of nuclear decay.
In nuclear equations, the sum of the atomic number and mass number on each side of the
equation should balance.
Alpha emissions
Beta emissions
Nuclear fission
In nuclear fission the nuclei of uranium or platinum break up into 2 smaller, lighter nuclei and
release a large output of energy;
Nuclear fusion
Nuclear fusion is the reverse of nuclear fission. Two light nuclei are fused together to produce a
heavier nucleus.
This reaction takes place in the centre of stars, which have sufficiently high temperatures and
pressures to allow this reaction to take place.
Half-life
Stability (or rate of decay) of a radioisotope is measured in half-life.
The decay of an unstable nucleus is a random event and is independent of chemical or physical
conditions.
The half-life of a radioisotope is the time taken for the sample's activity to fall by half, and can be
easily calculated.
Radioisotopes of elements have a wide variety of uses.
Cobalt-60 Used in medicine to treat cancer. rays can be focused on tumors.
Iodine- Used to treat thyroid gland (in the neck). If the gland is enlarged, iodine-133 can be
133
absorbed and will partially destroy it.
CarbonUsed to date once-living materials.
14
Carbon dating
Every living organism contains the radioisotope carbon-14. Carbon-14 is formed when neutrons
from cosmic radiation collide with nitrogen atoms in our atmosphere forming protons and
carbon-14 atoms.
Carbon dioxide is responsible for carbon-14 entering the food chain.
Carbon-14 decays by beta-emission and has a half-life of 5730 years. This means that the betadecay emissions can be monitored and the data used to calculate how long it has been since
the material was alive.
Organic
A homologous series is a family of hydrocarbons with similar chemical properties who share the
same general formula.
We will look at three series: alkanes, alkenes and the cycloalkanes.
Alkanes
The first homologous series is the alkanes. Their names all end in –ane.
The alkanes have many uses:
• methane – (natural gas) cooking, heating
• propane – used in gas cylinders for BBQ etc
• octane – used in petrol for cars
The general formula of the alkanes is
.
Naming branched chain alkanes
There are some general rules which you should remember when naming organic compounds:
• The longest unbranched chain containing the functional group is the parent molecule, or
simply the longest unbranched chain for alkanes. Remember that, the longest chain can
go round a bend.
• Indicate the position of the functional group with a number, numbering from the end
nearest the functional group.
• Name the branches, and indicate the number of branches.
Example
• Methyl indicates there is one carbon atom in the branch.
• Ethyl indicates there are two carbon atoms in the branch.
• The prefix 'di' indicates there are two branches.
• The prefix 'tri' indicates there are three branches.
Indicate the position of the branches with a number, numbering from the end nearest the
functional group.
For more than one branch, the branches are identified in alphabetical order, ignoring any 'di',
'tri', etc, prefixes.
Each branch needs to be numbered individually, even if they are attached to the same carbon
atom.
The rule is a comma between numbers, and a dash between numbers and letters.
Branched chain alkanes
The alkanes don't contain a functional group and so the branches are numbered from the end
that gives the lowest set of position numbers for the branches.
Use the above rules to see how the names of the alkanes below are built up.
Alkenes
The second homologous series is the alkenes. Their names all end in –ene, for example
ethene.
Alkenes all contain a carbon to carbon double bond which makes them more reactive than the
alkanes. The alkenes have the general formula
.
The alkenes are unsaturated. This means that they have a carbon to carbon double bond. The
alkanes are saturated because they only contain single bonds. An unsaturated hydrocarbon
decolourises bromine water quickly. Alkanes do this slowly. Alkenes can be used as fuels,
solvents and starting materials for everyday products such as plastics and vinegar.
Naming alkenes
Naming alkenes has the same rules as alkanes.
However, the position of the carbon to carbon double bond must be identified.
Cycloalkanes
The third homologous series is the cycloalkanes. Their names all end in –ane and begin with
cyclo-, for example cyclopropane. The cycloalkanes have the general formula
.
Even though they have the same general formula as the alkenes, the cycloalkanes are
saturated and contain only single bonds. This means that they do not quickly decolourise
bromine solution.
Many cycloalkanes are used in motor fuel, natural gas, kerosene, diesel and other heavy oils.
Combustion reactions
All hydrocarbons (including alkanes, alkenes and cycloalkanes) can undergo combustion
reactions with oxygen to give the same two products. Hydrocarbon fuels burn when they react
with oxygen in the air. As all hydrocarbons only contain the elements carbon and hydrogen, the
only products will be oxides of these elements. So as long as enough oxygen is present for
complete combustion, the two products formed will be carbon dioxide (CO 2) and water (H2O).
The word equation for this reaction is shown below.
The products from the combustion of hydrocarbon fuels can be identified with the following set
up in the lab.
Carbon dioxide gas turns limewater from colourless to milky white. In the above experiment, the
limewater in the boiling tube changes colour indicating carbon dioxide is produced by
combustion of the hydrocarbon fuel.
If water is produced it will condense in the U-tube cooled by the ice water. This results in cobalt
chloride paper changing the colour from blue to pink.
Incomplete combustion (when there is an insufficient supply of oxygen) could lead to toxic
carbon monoxide (CO) being produced instead of carbon dioxide
Energy from fuels
Combustion reactions
Many different compounds can be used as fuels, most commonly alkanes and alcohols. When
these fuels burn, they release heat energy and light energy to the surroundings in exothermic
reactions. Endothermic reactions take in heat energy.
These reactions are known as combustion reactions and can be represented by different
equations.
For example, propane gas tanks are commonly sold on petrol station forecourts. These gas
bottles have a wide variety of uses including portable heating and cooking for caravans and
barbecues.
When propane burns in a plentiful supply of oxygen, it produces both carbon dioxide and water.
This change can be represented by a word equation or a formula equation.
Word equation
Balanced formulae equation
A balanced formulae equation, along with the formula triangles you learned in Unit one can be
used to calculate information on the quantities of reactants or products involved in a particular
reaction.
Calculating the energy released when fuels burn
Exothermic reaction - a reaction in which energy is given out, usually in the form of heat.
The reaction gets hotter.
Endothermic reaction - a reaction in which energy is taken in. The reaction gets colder.
Some fuels are better than others at releasing energy during combustion reactions. The energy
released (sometimes called enthalpy) is calculated using the following equation:
is the heat energy released (in kJ or kJ mol-1)
is the specific heat capacity of water. It is a constant, 4.18 kJ kg -1 ˚C-1
is the mass of water (in kg) (100cm3 = 0.1kg)
is the change in temperature (˚C)
This formula is very easy to recall if you remember that "Every house can't make triangle toast!"
Addition reactions
Alkenes are more reactive than alkanes and cycloalkanes because they have a double bond.
While alkanes, alkenes and cycloalkanes undergo combustion reactions with oxygen, only
alkenes can participate in addition reactions.
In an addition reaction, the double bond of the alkene partially breaks when the reactant
molecule attacks and adds on across it.
Example
Addition of bromine water can be used as a test for unsaturation.
Alkenes quickly turn bromine water colourless, while alkanes and cycloalkanes do not.
The addition of bromine to an alkene is called bromination.
Other small molecules can be added across double bonds in alkenes. If hydrogen is added,
then the corresponding alkane molecule is formed.
Example
Isomers
Isomers are compounds with the same molecular formulae but different structural formulae.
Isomers are compounds with different physical and chemical properties but the same molecular
formula.
This diagram shows butane and methylpropane. (Methylpropane used to be called iso-butane,
but the correct name is methylpropane).
Butane
Both have a molecular formula of
are isomers of each other.
. The structural formulae are different though, so they
Other Organic
Alcohols, carboxylic acids and esters
Alcohols
Alcohols, also known as alkanols, have the hydroxyl functional group –OH. They are a
homologous series and have the general formula
. Their names all end in –ol.
The rules for naming an alcohol are the same as before. The hydroxyl functional group is the
most important part of the molecule and the carbon chain is numbered to give it the lowest
branch number.
Example
Butan-2-ol
The position of the functional group and any branches must be identified.
Alcohols have a wide variety of uses. While ethanol is most famous for its presence in alcoholic drinks,
many other alcohols exist and are commonly used as fuels and solvents. Propan-2-ol is widely used in
hand gels and disinfectant wipes. Alcohols are particularly useful as fuels due to their high flammability
and the fact that they burn cleanly
Carboxylic acids
Alkanoic acids
Carboxylic acids, also known as alkanoic acids, all contain the carboxyl functional group –
COOH. Their names all end in '–oic acid'. When naming carboxylic acids, the position of the
carboxyl group does not need to be identified with a number, as it is always found at the end of
the carbon chain, and so is on the first carbon.
Butanoic acid
One of the most widely used carboxylic acids is vinegar. Also known as ethanoic acid, it has far
more uses than simply being added to chips, and is commonly used in chemicals used to treat
limescale in bathrooms or inside kettles. Many foods are also preserved in vinegar (pickled) to
make them last for longer periods of time. Lots of other carboxylic acids have less pleasant
smells than vinegar and some are highly corrosive so must be handled with care.
Esters
Esters are formed by the condensation reaction between an alcohol and a carboxylic acid. This
is known as esterification. Esters have characteristic smells and are insoluble in water. They are
commonly used as fragrances and perfumes.
( means a reversible reaction)
They have the functional group:
(R means rest of the molecule.)
The functional group (-COO) is known as the ester link.
Naming esters
To name an ester:
• Change the alcohol name to end in –yl.
• Change the acid name to end in –oate.
• Alcohol name goes to the front, acid name to the back.
Example
The ester propyl ethanoate which is responsible for the distinct pear drop smell associated with
the sweet can be made by the condensation reaction between propanol and ethanoic acid.
Esters can be made in the lab using apparatus illustrated in the diagram below.
Polymers
Properties of plastics
Most of the plastics we use have been made by scientists from chemicals that were obtained
from crude oil.
Plastics are examples of polymers - very large molecules formed by the joining of many small
molecules called monomers. The uses of plastics are related to their chemical properties.
Naming polymers
The name of the polymer comes from the name of the monomer used to make it.
For example, the monomer ethene can be used to make the polymer poly(ethene).
Notice how the prefix poly- is put in front of the name of the monomer. Brackets are put around
the name of the monomer.
The table shows some examples of monomers and the names of polymers made from them.
Polymerisation
Polymerisation is the process in which the small monomer units join together to form a large
polymer molecule.
Addition polymerisation
Addition polymerisation is a process involving many small, unsaturated monomers combining to
form one large polymer molecule.
The alkenes ethene and propene are two important feedstocks in the petrochemical industry
which can also be used to make addition polymers.
How to draw structural formulae for polymers
The formation of poly(ethene) from ethene is an example of addition polymerisation. Small
unsaturated ethene monomers join up by the opening of the double bond allowing them to join
up to form a long carbon chain.
Polymers made in this way are called addition polymers.
The monomers used to make other addition polymers are drawn in a similar shape to ethene,
for example, propene.
Propene is the monomer for poly(propene)
Although this is the usual way to draw the structural formula for propene, for the purposes of
showing how the molecule acts as a monomer and can form a polymer it should be drawn in a
different way.
A propene molecule drawn in an 'H' shape - like ethene
Examples of other monomers are given below.
Given the structure of the monomer the structural formula of the addition polymer can be drawn.
For example
Condensation polymers
Condensation polymerisation is a process whereby many small monomer molecules join
together to form one large polymer, with water, or some other small molecule formed at the
same time. The monomers have more than one functional group.
Polyesters
Polyesters are condensation polymers formed by the reaction between a diacid with a diol. Both
monomers must have two functional groups.
Polyester monomers both have two functional groups
Polyesters are formed from condensation polymerisation
If you are asked to identify the monomers from a condensation polymer, simply add a water
molecule back across the ester link. This is called hydrolysis.
To break the ester link, firstly identify the ester link and then just add water.
Polyamides
Polyamides are condensation polymers made from a dicarboxylic acid and a diamine.
Polyamide monomers both have two functional groups
Polyamides all have the amide link.
An example of a polyamide is nylon. It is a very important engineering plastic.
Nylon's strength is related to the strong intermolecular bonds between the polymer chains and it
is unreactive to many chemical reagents.
Formation of nylon
Proteins
Nitrogen is an essential nutrient for all plants and animals, as it is needed to make proteins.
Proteins are natural condensation polymers formed by joining together thousands of amino acid
molecules.
Amino acids have a carboxyl group and an amine group
Protein formation
Two amino acids combine in a condensation reaction to form a protein and a water molecule.
Proteins have many important jobs within the body. They form the major structural materials of
animal tissue including hair, nails and muscle etc. Other proteins are involved in regulating life
processes. These include haemoglobin, enzymes and certain hormones like insulin.
pH Scale
pH is measured using Universal indicator, pH paper or a pH meter.
The scale can go from -1 to 15 but most substances lie between 1 and 14. Acids have a
pH < 7
Alkalis have a pH > 7
Neutral substances have a pH = 7.
The pH scale is dependent on the concentration of H +(aq) ions and is based on the fact that
water is partially ionised.
H20(1)
H+ (aq) + OH - (aq)
Acids and alkalis affect the pH when added to water, so change the H+ ion
concentration.
In water:
Concentration of H + = Concentration of OH -
In acids:
Concentration of H + > Concentration of 0H In alkalis:
Concentration of H + < Concentration of OH Soluble metal oxide form alkalis. Soluble
non-metal oxides form acids.
Fizzy drinks are acidic because of the carbon dioxide gas dissolved in them
Most cleaning compounds tend to be alkaline.
Effect of Dilution
Diluting an acid increases its pH towards 7. Diluting an
alkali decreases its pH towards 7. Diluting both reduces
their electrical conductivity.
Reactions of Acids
Neutralisation reaction: moves the pH of an acid to 7, producing water. Base: a
substance which neutralises an acid.
Salt: ionic compound formed from the negative ion of the acid and the positive ion
from the neutraliser (usually metal).
Acid
Type of salt
Hydrochloric
... chloride
Nitric
... nitrate
Sulphuric
... sulphate
Ethanoic
... ethanoate
1.
2.
3.
4.
5.
Acid + metal hydroxide (alkali) --> Salt + water
Acid + metal oxide --> salt + water
Acid + metal carbonate --> salt + water
Acid + ammonia → ammonium salt
Acid + metal --> salt + hydrogen
1 —4 are neutralisations, while 5 is a displacement.
The full balanced ionic equation for a neutralisation shows the true equation for the reaction is.
H+ + OH- --> H2O
Or
CO32- + H+ --> CO2 + H2O
(this is for metal carbonates as a base)
Alkalis are metal hydroxides (reaction 1 above) which are soluble in water.
Spectator ions: Ions which do not change during the reaction so don't actually take
part in the reaction.
Acid rain: caused by sulphur dioxide, nitrogen dioxide and carbon dioxide. Affect
buildings, structures and wildlife. Farmers use lime to neutralise the effects on soils
and lakes.
Precipitation: formation of an insoluble salt from 2 solutions.
How you know a precipitation reaction will take place:
Use the solubility data on page 5 of the databook.
1. Take the names of the 2 soluble chemicals you start with:
For example: lead nitrate + potassium iodide
2. Swap the 2 positive ions to make 2 new substances:
That is: lead iodide + potassium nitrate
3. If one of these compounds is insoluble, then a precipitation reaction will occur!
How to spot a precipitation reaction equation:
1. Check the state symbols.
2. The 2 reactants must both be (aq) and one product must be (s). Example:
Pb(NO3)2(aq) + 2KI(aq) —> PbI 2(s) + 2KNO 3(aq)
Titration Calculations
At the end point (neutralisation) of titration: Number
of H+ ions = Number of OH - ions So the
calculation is:
pCV (acid) = pCV (alkali)
where p(acid) = number of H + ions in formula
p(alkali) = number of OH - ions in formula
C = concentration and
V = volume (in litres)
Or… work out moles of own, use balanced
formula for moles of unknown, convert t to form
required.
Calculations
Any balanced equation can be used to calculate unknown quantities.
Step 1: calculate moles of known
Step 2: use ration for moles of unknown
Step 3: convert to form required
The Formula Mass is the total of the relative atomic masses (RAMS) in a formula of a
substance. This is measured in grams.
One Mole of any substance = Gram Formula Mass (gfm).
Converting between mass, moles and gfm is based on rearranging the formula.
N = m/GFM So…
m = N x GFM (m = mass in grams)
Balanced equations can be used to predict masses and numbers of moles of products.
The molar ratio of the balanced equation is used, eg. What mass of water would you get
from 19g of H 2?
2H2 + 02 —> 2H20
Molar ratio:
2
:
1
:
2
Ma ss ra ti o : 2 x g fm : 1 x g fm : 2 x g fm
So
4g
: 32g
: 36g
19g
: 152g : 171g
Or you can convert to moles and then use the ratio for the unknown to calculate it’s quantity in
the form required.
i.e 19g of H2 is
m/GFM = 19/2 = 9.5 moles of H2 (Diatomic element)
Therefore 9.5 moles of water produced as the ratio is 2:2 or 1:1
9.5 moles of H20 is NxGFM = 9.5X18 = 171g
In solutions, N= CV
Where N = number of moles (mol)
c = concentration ( mol/l )
V = volume in litres (I)
Metals
Metallic Bonding is positive metal cores in a sea of delocalised outer electrons. These
electrons flow in a direction when a charge is applied. This is conduction and metals are
very good at it. Why do you think Aluminium is such a good conductor?
Reactions with water
Metals can react with water, acid and oxygen. The reactivity of the metal determines which
reactions the metal participates in.
When metals react with water, metal hydroxides and hydrogen gas are formed. This can be
represented in different ways as shown:
Word equation
Calcium + water = calcium hydroxide + hydrogen
Chemical equation
Ca + 2H2O = Ca(OH)2 + H2
Ionic equation
Ca (s) + 2 H2O (l) = Ca2+(OH-)2 (aq) + H2 (g)
Reactions with acid
When metals react with acids, a salt of the metal and hydrogen gas are formed. The salt of the
metal is named following the rules you learned in Unit 1 of the course.
Word equation
Magnesium + Hydrochloric acid = magnesium chloride + Hydrogen
Chemical equation
Mg + 2HCl = MgCl2 + H2
Ionic equation
Mg(s) + 2H+Cl- (aq) = Mg2+(Cl-)2 (aq) + H2 (g)
Reactions with oxygen
When metals react with oxygen, metal oxides are formed.
Word equation
Chemical equation
Ionic equation
Summary
The reaction series of metals is as follows.