Periodicity

Question 1

Original Periodic Table

Answer 1

Created by Demitri Mendeleev (Russian scientist)
Arranged by increasing atomic mass (small –> big)
Empty gaps were left for elements he predicted by hadn’t been discovered yet

Question 2

Modern Periodic Table

Answer 2

Arranged by atomic number (small –> big)
Periodic repetition of chemical and physical properties

Question 3

Periods and Groups

Answer 3

Periods (rows) go left to right, there are 7 rows
Periods indicate the number of energy levels
Groups (columns) go top to bottom, there are 18 columns
8 groups are known as Families
Families share chemical and physical properties

Question 4

Group 1A (Alkali Metals)

Answer 4

1 valence electron
Hydrogen is NOT part of this family
Never found in a free state (always paired with something else)
Most reactive group of metals

Li Na K Rb Cs Fr
<———————————————–>
Least reactive Most reactive

Lewis Dot Diagram
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X

Question 5

Group 2A (Alkaline Earth Metals)

Answer 5

2 valence electrons
2nd most reactive group of metals
Never in a free state

Be Mg Ca Sr Ba Ra
<—————————————————>
Least reactive Most reactive

Lewis Dot Diagram
. .
X

Question 6

Group 3A (Boron Family)

Answer 6

3 valence electrons
3rd most reactive group of metals
Never in a free state

B Al Ga In Ti
<————————————->
Least reactive Most reactive

Lewis Dot Diagram
. .
X .

Question 7

Group 4A (Carbon Family)

Answer 7

4 valence electrons
Not very reactive
Contains metals, metalloids, and nonmetals

C Si Ge Sn Pb
<—————————————>
Not metal Metal

Lewis Dot Diagram
. .
X .
.

Question 8

Group 5A (Nitrogen Family)

Answer 8

5 valence electrons
Not very reactive
First group of mostly non-metals (first to contain gas)

N P As Sb Bi

Lewis Dot Diagram
. .
. X .
.

Question 9

Group 6A (Oxygen Family)

Answer 9

6 valence electrons
Reactive non-metals (O, and S)

O S Se Te Po

Lewis Dot Diagram
. .
. X . .
.

Question 10

Group 7A (Halogens)

Answer 10

7 valence electrons
Most reactive group of non-metals
Never found in a free state
Poisonous to ALL life

F Cl Br I At

Lewis Dot Diagram
. .
. X . .
. .

Question 11

Group 8A (Noble Gasses)

Answer 11

AKA inert gasses
8 valence electrons (except for He)
Complete outer shells
Most non-reactive family
Does not react naturally with anything

He Ne Ar Kr Xe Rn

Lewis Dot Diagram
. .
. . X . .
. .

Question 12

Transition Metals

Answer 12

Not a family/group
D block
Found in a free state
Valence and charges vary
Valence electrons vary

Question 13

Inner Transition Metals

Answer 13

Not a family/group
F block (Lanthanide series #58-70, Actinide series #90-102)
Mostly man made elements
Valence electrons vary

Question 14

What about Hydrogen?

Answer 14

Can gain AND loose it’s 1 valence electron
Not in a family
Very flammable
Diatomic (can react with itself, H2)

Question 15

Metallic Character (periodic trends)

Answer 15

Having qualities of a metal
The further right you go on a periodic table the less metal like an element is
The further down the more an element becomes metallic (metal like)

Question 16

Size of Atom (periodic trends)

Answer 16

Atomic radius = size of the atom
Distance between two nuclei divided by two
More shells / further down in the periodic table the larger the atom
As you go across (left -> right) the size shrinks (same amount of shells just closer together)
More attraction in the atom the further right on the periodic table
The closer to Cs, the larger the atom

Question 17

Shielding Effect (periodic trends)

Answer 17

Blocking the protons pull on valence electrons by energy levels between them
More shielding effect —> weaker pull

Question 18

Effective Nuclear Charge, Zeff (periodic trends)

Answer 18

Protons in the nucleus pulling on the valence electrons
More shields —-> weaker pull
Shielding effect is constant
Further right the more positive/excited the nucleus is

Question 19

Ionization Energy (periodic trends)

Answer 19

The amount of energy needed to REMOVE an electron
The further right the smaller in size and the stronger the Zeff
Further down the larger in size and weaker the Zeff
Further right the higher the ionization energy
Further down the lower the ionization energy

Question 20

Stability of Subshells (periodic trends)

Answer 20

The further right on the periodic table you go the more energy it takes to remove, and the more stable the atom
The further left on the periodic table you go the less energy it takes to remove, and the less stable the atom

Question 21

Electronegativity / Electron Affinity (periodic trends)

Answer 21

The atoms want for an additional electron
The further right the higher the want for an electron
Caused by the octet rule
The higher the Zeff the higher the want for an electron
Noble gasses DO NOT want any electrons (no affinity)
The greater the shells the weaker the affinity

Question 22

Activity of Metals (periodic trends)

Answer 22

A metal being VERY reactive (Alkali Metals)
Metals want to lose electrons to achieve octet
Metals have a low Zeff
Metals have low ionization energy
Metals have high electron shielding
Cs = Most reactive of all metals
The further right the least reactive a metal is
The further down the more reactive a metals is

Question 23

Activity of Non-metals (periodic trends)

Answer 23

A non-metal being VERY reactive (Halogens)
Non-metals want to gain electrons to achieve octet
Strong Zeff
High ionization energy
High electron affinity
F = Most reactive halogen
The further right the more reactive a non-metal is
The further down the less reactive a non-metal is

Question 24

Cations

Answer 24

Cations are smaller than the parent ion

Question 25

Anions

Answer 25

Anions are larger than the parent ion