Transcript Chemistry Notes

Periodic Table
Notes
• Periodic Table –
An arrangement of the elements in order
of their atomic numbers so that elements
with similar properties fall in the same
column or group.
Atomic Number
6
Atomic Symbol
C
Name
Atomic Mass
Carbon
12.011
• Atomic Radius –
One half the distance between the nuclei
of identical atoms that are bonded
together.
• Trend
– Increases as you go down the groups
– Decreases as you go across the periods
I
N
C
R
E
A
S
E
A.R.
DECREASE
Trends Sample 1
Of the elements magnesium, Mg, chlorine,
Cl, sodium, Na, and phosphorus, P, which
has the largest atomic radius? Which has
the smallest?
1. Find atoms on the periodic table
2. Compare to trend
– Decreases as you go across the period
•
•
Largest atomic radius = Sodium, Na
Smallest atomic radius = Chlorine, Cl
Trends Sample 2
Of the elements calcium, Ca, beryllium, Be,
barium, Ba, and strontium, Sr, which has
the largest atomic radius? Which has the
smallest?
1. Find atoms on the periodic table
2. Compare to trend
– Increases as you go down the groups
•
•
Largest atomic radius = Barium, Ba
Smallest atomic radius = Beryllium, Be
• Ion –
An atom or group of bonded atoms that
has a positive or negative charge.
• Ionization Energy –
The energy required to remove one
electron from a neutral atom of an
element.
• Trend
– Decreases as you go down the groups
– Increases as you go across the periods
D
E
C
R
E
A
S
E
I.E.
INCREASE
• Cation –
Positively charged ion.
• Anion –
Negatively charged ion.
• Valence Electrons –
The electrons available to be lost, gained,
or shared in the formation of chemical
compounds.
Valence Electrons in Main Group Elements
Group
Number
Group
Configuration
Number of Valence
Electrons
1
s1
1
2
s2
2
13
s 2p 1
3
14
s2p2
4
15
s 2p 3
5
16
s 2p 4
6
17
s 2p 5
7
18
s 2p 6
8
• Electronegativity –
The ability of an atom in a chemical
compound to attract electrons.
• Trend
– Decreases as you go down the groups
– Increases as you go across the periods
– Nobel gases have no electronegativity (they
do not want electrons)
D
E
C
R
E
A
S
E
EN
INCREASE
• Fluorine is the most electronegative
element (wants an electron the most) and
is therefore assigned the highest value of
four.