Ch 2 - Periodic Table

Question 1

How are valence electrons represented on the periodic table?

Answer 1

Roman number above each column

Question 2

What are A elements?

Answer 2

“Representative elements”

IA to ViiiA

The valence electrons of these groups are in the s or p shells

Question 3

What are B elements

Answer 3

“Nonrepresentative elements”

Includes transitional elements
(Valence in shells s and d)

And lanthanide and actinide series (valence in s and f subshells)

Question 4

METALS

Gen info

+ 2 properties

+ 3 atomic properties

Answer 4

Left and centre of periodic table
(Active metals: s subshell)
(Transition metals: d subshell)

Gen high density and high melting points
Generally lustrous solids except mercury which is liquid at reg temp

Malleable and ductile

High electro-positivity
Low ionization energy
Easily give up electrons

Question 5

What are transition metals?

Answer 5

Group B elements

Valence electrons in d subshell

Many have 2 or more OXIDATION STATES aka charges when forming bonds with other atoms.

Because the valence electrons readily nice around, this makes them good conductors of heat and electricity.

Question 6

Where are lanthanide and actinide series elements found?

Answer 6

In the section if the f subshell (bottom of periodic table)

Question 7

NON METALS

Answer 7

Upper right of periodic table

Brittle in their solid state

High ionization
Electron affinities
Electronegativities
(OPPOSITES of metals)

Don’t give up electrons easily

Question 8

METALLOIDS

Answer 8

“Semi-metals”

Stairs starting from B

Have some metal and some nonmetal properties
Generally are good semiconductors due to their partial conductivity

Question 9

What is effective nuclear charge?

Z-eff

Answer 9

A measure of the net positive charge (from the protons) experienced by the outermost electrons

THE PULL OF THE PROTONS AS EXPERIENCED BY THE ELECTRONS

Hence, in one PERIOD, the Z-eff increases as the number of proton/electron increases

Question 10

Principal quantum number and it’s relation to the periodic table:

Answer 10

As we go down a GROUP, the principal quantum number increases

(Hence the other shells if electrons are creating more and more of a reduction in the pull from the proton)

Question 11

Which group are the noble gases?

Answer 11

Group 18 - far right

Question 12

Periods versus groups

Answer 12

Periods - rows
Groups /families - columns

Each item on a row has 1 more proton and 1 more electron that the element before it

Each item in a group has similar electronic configuration in the valence shell and share similar chemical properties

Question 13

Atomic radius

Answer 13

Half the distance between the centre if two atoms of an element that are briefly in contact with each other

OPPOSITE of all other trends: decreases across periodic table from L to R

Question 14

What is Z-eff?

Answer 14

The effective nuclear charge: the PULL ON THE ELECTRONS

Increases across a period (left to right)

Question 15

What is ionic radius?

Answer 15

Related to how many electrons the metals/NM/MO’s are going to gain or lose to make an octet, and how that electron charge/pull related to that of the nucleus

Metals near the METALLOIDS line have MORE electrons to give up, compared to strong nucleus pull so the ionic radius is smaller.

Nonmetals near the METALLOIDS line need more electrons to make an octet, hence the ionic radius is larger because they gain electrons while the nucleus stays the same

Question 16

What is ionization potential / ionization energy?

Answer 16

The energy needed to remove an electron from a gaseous species

Requires input of heat = endothermic process (heat is taken in)

Higher Z-eff - higher ionization energy needed

Question 17

What are “active metals”?

Answer 17

Metals that give up their electrons very easily (have very low Z-eff hence need low ionization energy)

DONT EXIST IN THEIR NEUTRAL FORMS - always in an ionic compound

ie lithium, beryllium

Question 18

First ionization and second ionization energies

Answer 18

The energies requires to remove he first electron, the second, and so on.

The second ionization is greater since the electron is being removed from an increasingly cationic (positive) species

Second ionization in Group 1 monivalent cations is especially very high because after the first electron is removed, it has a stable octet configuration!

Question 19

Electron affinity : is it endothermic or exothermic?

Answer 19

EXOTHERMIC

Gives off heat when an electron is gained

Question 20

Electronegativity - how is it determined?

Answer 20

Determined by the ionization energy

High I.E = high electroneg

Question 21

Most and least electronegative elements?

Answer 21

Cs - LEAST
Least electronegative
Lowest ionization energy
Least electron affinity

F - MOST
Most electronegative
High ionization energy
Most ectothermic electron affinity

Question 22

ALKALI METALS

Answer 22

Group 1
1 valence electron

Low Z-eff
Largest atomic radii
Low electronegativity, low ionization energy, low electron affinity

Readily react w Nonmetals, esp Halogens

Harsh reactions with water and air

Question 23

ALKALINE EARTH METALS

Answer 23

Group 2 - 2 valence electrons

Slightly higher Z-eff than alkalis
Slightly smaller atomic radii than alkalis

ALKALI METALS AND ALKALINE EARTH METALS are active metals
(Very reactive, bit usually found in their neutral state)

Question 24

CHALCOGENS

Answer 24

Group VIA - 6 electrons
CRUCIAL FOR BIOLOGICAL FUNCTIONS

Nonmetals and metalloids
Generally have small atomic radii, large ionic radii

Many of these substances in high concentrations can be damaging or toxic

Question 25

HALOGENS

Answer 25

Group VIIA - 7 electrons

Halogens can be gas, liquid (Br) or solid (I)

Large Z-eff value
Small atomic radii
High electronegativity, high electron affinity,

**rarely found in neutral states: often found as HALIDES, aka ions

Question 26

NOBLE GASES

Answer 26

Group VIIIA - full octet

“Inert gases” because they have low reactivity

High ionization energy, no or low electron affinity, and usually no measurable electronegativity.

VERY low boiling points - all are gases at room temp

Question 27

TRANSITION METALS

Role in biology?

Answer 27

B groups (3-12, entire middle)

"Metals"
Low electron affinity
Low ionizing energy
Low electronegativity 
Large atomic radii 

Good conductors, malleable (loosely held electrons)
Very hard, high boiling points

**many of these are cofactors for enzymes

Question 28

Oxidation states of TRANSITION METALS

Answer 28

They are able to have a varied number of electrons missing, so varied positive charges (or Cu+, Cu2+)

Because of this ability to maintain different positive oxidation states, they can form many different compounds.

Diff oxidation states = diff COLORS