Download Elements Combine to Form Compounds

Elements Combine to Form Compounds
Name the Super – Heroes
Compound – “Pun”
Compound - “Pun”
Compounds ( 2nd type of Pure Substance)
 Compound: a pure substance made up of more than
one kind of element in which the atoms
of the elements are joined together.
 Compounds form through chemical bonds:
 these are links between two or more atoms that hold
the atoms together
 Two types of Compounds (chemical bonds)
 Ionic Compounds
 Molecular (covalent) Compounds
Compounds…
 Compounds are represented by a combination of element
symbols known as a chemical formula:
 Chemical Formula (tells us):
 type of elements (atoms)
 proportion (number) of each atom involved
 CH4
Elements Present
Carbon and Hydrogen
 NaCl
Sodium and Chlorine
Proportion: (# of each element)
1 carbon atom and 4 hydrogen atoms
1 sodium atom and 1 chlorine atom
Two types of compounds
Molecular (covalent) compounds:
 formed between non- metals only
 this type of bonding involves sharing of electrons
 Examples: (we need to know)
 1) Carbon Dioxide (gas) - CO2
 2) Water - H2O
 3) Sucrose (table sugar) – C12H22O11
 4) Methane (gas) – CH4
Ionic Compounds
 formed between metals and non-metals.
 this type of bonding involves atoms attracting to each other
because of opposite charges
(+) (-)
 the atoms involved either gain or loose electrons to form
charged particles called Ions (positive or negative)
 Examples: (we need to know)
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1) Sodium Chloride (salt) - NaCl
2) Calcium Carbonate (chalk) - CaCO3
3) Sodium Sulfate (salt) - Na2SO4
4) Sodium Hydroxide (drain cleaner) – NaOH
Molecular (Covalent)
“share”
Ionic
“give away and “charge”
Ionic Compounds - “Ions”
Counting Atoms
Chemical Formula
Elements Involved
Number of Atoms
CO2
Carbon (C)
Oxygen (O)
3 atoms - 1 carbon (C)
- 2 oxygen (O)
MgCl
Magnesium
(Mg)
Chlorine (Cl)
2 atoms
Na2SO4
Sodium (Na)
Sulphur (S)
Oxygen (O)
7 atoms - 2 Sodium (Na)
- 1 Sulphur (S)
- 4 Oxygen (O)
C12H22O11
Carbon (C)
Hydrogen (H)
Oxygen (O)
??? atoms – ___ carbon (C)
___ hydrogen (H)
___ oxygen (O)
- 1 magnesium (Mg)
- 1 chlorine (Cl)
Chemical Formulas
Chemical Names of Compounds
 When given a chemical formula, you can write the
chemical name which indicates the elements present
in the compound
 IUPAC (International Union of Pure and Applied
Chemistry)
 a group that represent chemists around the world and is
responsible for the rules when naming compounds.
 Ionic and Molecular compounds have their own set of
rules to follow.
Naming Compounds
 Set of rules that you have to follow when writing the
names for Ionic and Molecular Compounds.
 Basic steps:
 determine the elements involved in the chemical
formula (compound)…. Metals and Non- Metals
 determine the type of compound (Ionic or Molecular)
 follow the rules outline for Ionic or Molecular
Naming Ionic Compounds
 formed between metals and non-metals.
 Rules:
1) Name the first element (atom)
2) Name second element by ending the name
with the suffix “ide”
3) Put the two names together
Example of a Ionic Compound
 Example :
name for the compound
NaCl
Na (sodium) - metal
Cl (chlorine) - non- metal
 Name:
Sodium chloride
Naming Molecular (covalent) Compounds
 formed between non-metals.
 numbers (subscripts) are important and have to be
used at the beginning of each element in the naming
of the compound. ……(see page 83)
 Rules:
1) Name the first element (atom)
2) Name second element by ending the name with the
suffix “ide”
3) Add the “prefix” to the element names to show the
number of atoms in the compound
Example of a Molecular (covalent) Compound
 Example :
name for the compound
CO2
C (carbon) - non-metal
O (oxygen) – non- metal
CO2
[Have to use Prefix to show number of atoms in compound]

Name : Carbon dioxide
Prefixes (table 3.4, page 83)
Number of atoms
Prefix
1
Mono (used only for the second atom)
2
di
3
tri
4
tetra
5
penta
6
hexa
7
hepta
8
octa
9
nona
10
deca
Name the following compounds
 Mg3P2
Mg (metal)
Magnesium
P (non –metal) ….. Ionic
Phosphorus
 Numbers are NOT important …
 Name:
Magnesium phosphide
Name the following Compound
 N2O3
N (non-metal) O (non-metal) …..Molecular (Covalent)
Nitrogen
Oxygen
 Numbers are important
 Name :
N2O3
Dinitrogen trioxide
Try These ???
1) Ag3N -
2) CCl4 -
Physical Changes
 Physical Change
 a change in matter in which NO new substances are
produced
 the appearance of a substance may be changed but the
bonds between the particles (atoms) have not broken
 atoms either move closer together or farther apart
 Examples - change of state [freezing, melting …]
- dissolving [sugar in water]
- cutting paper
Chemical Changes
 Chemical Change
 a change in matter in which NEW substances are produced
with NEW properties.
 Clues that May Indicate a Chemical Change
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A new color appears
Heat or light is given off during the change
Bubbles or gas are formed
Solid clumps (precipitate) forms in the liquid
The change is difficult to reverse
 Examples: - Corrosion [metals rusting]
- Combustion [burning]
- Fruit Ripening
Chemical Changes and Chemical Reactions
 Chemical Changes also referred to a Chemical Reaction
 In every chemical reaction there is something used up and
something produced (made)
Reactants
Products
 Magnesium + Hydrochloric Acid → Hydrogen + Magnesium Chloride
 Sodium + Chlorine ------------------→ Sodium Chloride
The END !!!!!