Download PERIODIC TABLE OF THE ELEMENTS

TEST REVIEW: PERIODIC TABLE
1.
2.
Know the subatomic particles and their charges.
Know how to read a periodic table (rows, periods, electronegativity) and
apply that information to chemical equations.
3. Be able to compare and contrast the different groups of the periodic
table.
4. Know how to write the Lewis Dot Structures for groups 1-2, & 3A8A(remember group 3A = group 13 and cetera).
5. Know how valence electrons and orbitals relate.
6. Know what orbitals are.
7. Know and understand elements and ions.
8. Know how to break a compound down into its ionic components using
Lewis dot structures and valence electrons.
9. Be able to compare and contrast, atomic number, atomic weight and
mass number.
10. Be able to find molar mass (using the CORRECT set-up; as shown in
class).
11. Be able to compare and contrast different chemical reactions.
12. Be able to apply the Law of Conservation of Mass.
The periodic table
• Atoms are comprised of:
– Protons
– Neutrons
– Electrons
– Protons
• Positively charged subatomic particles
• ALL protons located within the atom’s nucleus
– Electrons
• Negatively charged subatomic particles
• All electrons are located ‘outside’ of the atom in its ORBITALS
– Neutrons
• Have NO CHARGE
• Located INSIDE the nucleus along w/ the protons
The periodic table
• Each element is located in
– A vertical column called a GROUP
– A horizontal row called a PERIOD
The periodic table
A vertical column is called a GROUP
The periodic table
A horizontal row is called a PERIOD
GROUP 1 = ALKALI METALS
– Hydrogen is not an alkali metal
– As with all families, these elements share traits.
• They are very reactive.
• Why?
• They all have one electrons in their outer shell
• Group 1 contains:
‒
‒
‒
‒
‒
‒
Lithium (Li)
Sodium (Na)
Potassium (K)
Rubidium (Rb)
Cesium (Cs)
Francium (Fr)
GROUP 2 = ALKALINE EARTH METALS
• The second most reactive group of elements.
•
They are called alkaline b/c when these
compounds are mixed in solutions:
– Likely to form solutions with a pH greater than 7.
•
A high pH solution is defined as a "basic" or "alkaline"
solution.
GROUP 2 = ALKALINE EARTH METALS
– Each has two electrons in their outer shell.
– Likely to give up those two electrons in
electrovalent/ionic bonds.
• Group 2 contains:
‒
‒
‒
‒
‒
‒
Beryllium (Be)
Magnesium (Mg)
Calcium (Ca)
Strontium (Sr)
Barium (Ba)
Radium (Ra)
GROUPS 3-12 = TRANSITION METALS
Groups 3-12 contain:
•
•
•
•
21 (Scandium) through 29 (Copper)
39 (Yttrium) through 47 (Silver)
57 (Lanthanum) through 79 (Gold)
89 (Actinium) and all higher numbers
GROUPS 3-12 = TRANSITION METALS
• Transition metals are good examples of advanced
shell and orbital ideas.
• They have a lot of electrons and distribute them
in different ways.
• Transition metals are usually shiny.
– E.g. silver (Ag), gold (Au), and platinum (Pt)
• Most elements can only use electrons from their
outer orbital to bond with other elements.
• Transition metals can use the two outermost
shells/orbitals to bond with other elements.
GROUP 17 = HALOGENS
• The halogens have seven electrons in their outer
shell.
• Instead of this making them more stable, they are
actually VERY reactive
‒ Can anyone guess why?
‒ Are we there yet, syndrome…
‒ Often will form bonds with metals and elements from Group 1.
• Group 17 contains:
‒
‒
‒
‒
‒
Fluorine (F)
Chlorine (Cl)
Bromine (Br)
Iodine (I)
Astatine (At)
GROUP 18 = NOBLE GASES
• Also known as GROUP ZERO
• The happiest of elements
– Have 8
electrons in their outer M electron shell.
• Non-reactive, but still used industrially & daily
– Neon lights (Las Vegas, your local nail shop)
– Used in industrially to stabilize reactions which would
otherwise proceed too quickly
• Group 18 contains:
–
–
–
–
–
–
Helium (He)
Neon (Ne)
Argon (Ar)
Krypton (Kr)
Xenon (Xe)
Radon (Rn)
Lewis dot structures: Valence Electrons
• Valence Electrons:
–Outer shell electrons
–Electrons in the highest occupied energy
level of the atom
–The only electrons involved in bond
formation (for most elements).
• Shared or given/taken away.
Lewis Dot: Bohr Atomic
Structures
• The first energy level can contain two
electrons
• The second and third levels can
contain 8 electrons
• Beyond the third level, energy levels
can contain 18 or up to 32 electrons
Lewis Dot Structures: What are they?
• What are Lewis Dot
Structures?
– Also known as electron dot
structure or Lewis dot
diagrams
– A notation showing the
valence (outer shell)
electrons surrounding an
atom.
Lewis Dot Structures: How To
• Figure out which group (column) the element of
interest lives in.
• This will tell you the number of valence electrons
of the element.
• For these diagrams you draw ONLY the VALENCE
electrons
Lewis Dot Structures: How To
• Write the symbol for the element.
• Nitrogen is in group 5A, so it has 5
valence electrons.
• Starting at the right, draw the 5
electrons clockwise around the
element symbol
N
Lewis Dot Structures
Elements within the same group have the same
electron-dot diagrams. REMEMBER THESE DIAGRAMS
ARE INCORRECT BUT THE # OF ELECTRONS IS CORRECT!
Remember: Electronegativity trend
Electronegativity is a measure of the tendency of an atom to attract
(or take) a bonding pair of electrons.
ORBITALS
ORBITALS
• Not all shells hold the same number of
electrons.
• For the first eighteen elements, there are
some easy rules:
– The K shell only holds two electrons.
– The L shell only holds eight electrons.
– The M
shell only holds eight electrons.
• The M shell can actually hold up to 18 electrons as you move to higher
atomic numbers.
– The maximum number of electrons you will find in any shell is
32.
• For our purposes, we’re only going to focus on the elements
having an M SHELL (it is happiest with 8 electrons).
ORBITALS
• Electrons are always moving.
• They orbit very rapidly around an atom’s
nucleus.
• Each electron has a ‘shell’ , or orbit in which it
must remain.
– Electrons in the first shell are closer to the nucleus
– Electrons in the outer shell are the furthest away from the
nucleus
– The further an electron is from the nucleus the more likely
that it is not:
• As stabilized by the positive charge of the nucleus (as are electrons
closer to the nucleus)
• And therefore, electrons in the outer shells are usually ‘not happy.’
ELEMENTS & IONS
• A neutral atom has:
–Equal numbers of protons and electrons
–A neutral atom is termed an ELEMENT
• An element becomes charged when:
–The number of its protons and electrons
becomes different
–A charged atom is termed an ION
ELEMENTS & IONS
𝑵𝒂 →
+
𝑵𝒂
• The Na atom:
–Lost an electron
–Became Positively charged
–Is now a CATION
• A cation is a POSITIVELY charged ion.
ELEMENTS & IONS
𝑪𝒍 → 𝑪𝒍• The Cl atom:
– Gained an electron
– Became Negatively charged
– Is now an ANION
• An anion is a NEGATIVELY charged ion.
• I remember it by: A
Negative ion = ANION
ATOMIC NUMBER, ATOMIC WEIGHT &
MASS NUMBER
• The atomic number (Z):
– Equals the number of protons in an
atom
– The number of protons is what
distinguishes one element from
another
– All atoms of a given element have
the SAME NUMBER of protons
• The mass number (A):
– Equals the number of protons &
neutrons in an atom.
ATOMIC NUMBER, ATOMIC WEIGHT &
MASS NUMBER
• The atomic weight
(or atomic mass):
‒ How much one atom
of an element weighs
‒ Measured either in
amu or g/mol
Determining Molar Mass
Each mole of methane
contains ONE mole of
carbon atoms and FOUR
moles of hydrogen
𝑚𝑎𝑠𝑠 𝑜𝑓 1 𝑚𝑜𝑙 𝐶 =
𝑚𝑎𝑠𝑠 𝑜𝑓 1 𝑚𝑜𝑙 𝐻 =
12.011 𝑔
+ 1.008 𝑔× 𝟒
𝑚𝑎𝑠𝑠 𝑜𝑓 1 𝑚𝑜𝑙 𝐶𝐻4 = 16.04g
This is referred to as the molar mass of methane (CH4).
Determining Molar Mass
𝑚𝑎𝑠𝑠 𝑜𝑓 1 𝑚𝑜𝑙 𝐶 =
𝑚𝑎𝑠𝑠 𝑜𝑓 1 𝑚𝑜𝑙 𝐻 =
12.011 𝑔
+ 1.008 𝑔 × 𝟒
𝑚𝑎𝑠𝑠 𝑜𝑓 1 𝑚𝑜𝑙 𝐶𝐻4 = 16.04g
Now convert the molar mass of methane to
molecules of methane.
Hint: Use Avogadro’s number
Hint #2: 1 mol = 6.022*1023 molecules
𝟏 𝒎𝒐𝒍 𝑪𝑯𝟒
𝟔. 𝟎𝟐𝟐 ∗ 𝟏𝟎𝟐𝟑 𝒂𝒕𝒐𝒎𝒔 𝒐𝒇 𝑪𝑯𝟒
×
=
𝟏𝟔. 𝟎𝟒 𝒈
𝟏 𝒎𝒐𝒍
Chemical Equations
• What is a “chemical equation”?
– “A chemical equation is the symbolic representation of a chemical
reaction wherein the [reactants] are given on the left hand side
and the [products] on the right hand side.
– The coefficients next to the symbols and formulas of [atomic]
entities are the absolute values of the stoichiometric numbers.”*
𝑨+𝑩→𝑪+𝑫
(REACTANTS)
(PRODUCTS)
2HCl + 2Na → 2NaCl + H2
coefficients
subscript
CHEMICAL REACTIONS
• Precipitation Reaction
– A reaction wherein the mixture of two solutions
form a solid which separates out of the solution
• Acid-Base Reaction
– A reaction wherein acids or bases interact and
exchange either Hydrogen atoms or electrons
• Oxidation-Reduction reaction
– A reaction involving the exchange of electrons
between reactants
LAW OF CONSERVATION
• Through countless experiments conducted in the
1700s, scientists were able to make a number of
discoveries in the field of chemistry.
• One such discovery involves the weighing of reactants
and products of chemical reactions.
• This led to the idea that mass is neither created
nor destroyed, but that it is conserved.
• This is called the Law of Conservation of Mass
• The same concept can be applied to energy.