• Use page to
make notes
• Liquid at
room
temperature:
BROMINE
•AND
Vertical
MERCURY
Columns:
I
VIIII
II
III
IV
V
VI
VII
GROUPS
•
•
•
•
•
•
•
•
• Metals:
• Horizontal
MOSTLY
Rows:SOLIDS
PERIODS
• Non-metals:
MOSTLY
• Elements
GASES
arranged
according to
7 diatomic
INCREASING
elements:
𝑯𝟐ATOMIC
𝑵𝟐NUMBER
𝟎𝟐 (position)
𝑭𝟐
𝑪𝒍𝟐
𝑩𝒓𝟐
𝑰𝟐
1 2 3
14
13
16
15
18
17
• VALENCE ELECTRONS = GROUP NUMBER
Number of electrons in outermost energy level
• 𝟏𝒔𝟐
• 𝟏𝒔𝟐 𝟐𝒔𝟐 𝟐𝒑𝟔
• 𝟏𝒔𝟐 𝟐𝒔𝟐 𝟐𝒑𝟔 𝟑𝒔𝟐 𝟑𝒑𝟔
• LAST ENERGY LEVEL= PERIOD NUMBER
ELEMENTS IN THE SAME GROUP
HAVE THE SAME VALENCE
ELECTRON STRUCTURE
• Metals:
Reactivity
increases from top to
the group
Potassium is more reactive
bottom in
than sodium
• Non-metals: Reactivity
increases
from bottom to
top in a group
Fluorine is more reactive than iodine
• Metals & Non-metals:
Reactivity increases
from right to left in
period
a
• Atomic mass
increases from
left to right in a
period
• Atomic mass
increases from
top to bottom a
group
• Density increases
from left to right
in a period
• Density increases
from top to
bottom a group
• Hoe werk dit???
• Intermolecular theory
• Dink aan atomic mass en
nommer van paticles.
• Forces – stronger – closer
together – density
increases.
• Metals (solid) – non
metals (gas) – move
apart – less force –
density decreases.
• Hoe werk dit?
• The stronger
the
• Metals:
M&B
points
intermolecular
forces
the
decrease
from
greater the
energy
needed to
top
to
bottom
break the
inforces
a group
• Strong intermolecular forces
cause melting points and
boiling points
increase
M & Btopoints
increase
from
left
• So the melting
and
boiling
tolarge
rightmolecules
in a period.
points of
with
strong intermolecular forces
are high
• Non-metals: M & B points
increase from
top to bottom
in a group
M & B points
decrease from left
to right in a period.
•
`
• Atomic radius
decreases from left
to right in a period
• Hoe werk dit?
• As the atomic mass increases,
the number of protons in the
nucleus increases
• The nucleus exerts a stronger
attractive force on the
electrons causing them to
move closer to the nucleus
and thus decreasing the
radius
• Atomic radius
increases from top to
bottom in a group as
the amount of energy
levels increases.
• Definition: The energy
required to remove one
electron from an atom in
• CATIONS
the
gaseous phase
Low ionisation energies
• The first ionization
energy
to remove first
• ANIONS
electron, 2nd IE 2nd
• High ionisation
energies
electron
etc
• IE increases from top to
bottom
in aGeneral
group.
• Discuss
• Greater
the IE – more
observations
page 91
difficult it is to remove
an electron.
1. Position on the
periodic table
2. Valence electrons
3. Atomic radius
• The tendency of an
atom to accept an
electron and form a
negative ion (anion)
• Energy is released
during the process
• DEFINITION
E.A. is the amount of
energy released
when a neutral atom
in the gaseous state
accepts an additional
electron
• The ability of an
atom to attract an
electron.
• DEFINITION
• The electro negativity of
an atom is a measure of
the attractive force of an
atom for the bonding
pair of electrons
between the two atoms.
• It is therefore an
indication of the
bonding ability of the
element.
• Increases from bottom
to top in a group.
• Increases from left to
right in a period.
Homework:
Summary of Periodicity
Exercise 7 pg. 94
Hopefully classwork
Test Examples