Module 3 Chapter 7

Question 1

What did Dmitri Mendeleev do

Answer 1

He is one of the main chemists credited with the development of the periodic table

Question 2

How did Mendeleev organise the periodic table

Answer 2

He organised elements by atomic mass
He placed elements into groups of which they shared similar chemical properties with
He left gaps where no known elements fitted with the chemical properties of the group

Question 3

What were the properties of the periodic table in the past

Answer 3

60 elements ordered by atomic mass
groups with similar properties
Properties had to fit, elements swapped and gaps left
Assumed incorrect atomic masses and some not discovered
Predicted properties of missing elements using group trends

Question 4

What are the properties of the periodic table now

Answer 4

118 elements
Vertical groups and horizontal periods
Elements arranged in increasing atomic number

Question 5

How are elements arranged in the periodic table

Answer 5

They are arranged in increasing atomic number

Question 6

What are the properties of groups in the periodic table

Answer 6

In each group the elements have atoms with the same number of electrons in the outer shell and similar properties.

Question 7

What does the period show

Answer 7

The number of the period gives the highest energy shell in an elements atom

Question 8

What is periodicity

Answer 8

The repeating trend of properties across the period

Question 9

What determines the chemistry of an element

Answer 9

A lot of the chemistry is determined by electron configuration, particularly the highest energy outer shell.

Question 10

What are some trends in periodicity

Answer 10

Ionisation energy
Structure
Melting points

Question 11

What is the trend of the highest energy sub shell where the electrons are held as you go across period 2, 3 and 4

Answer 11

Across period 2: 2S —> 2P
Across period 3: 3S —> 3p
Across period 4: 4S —> 3D —> 4P

Question 12

How many groups are in the periodic table

Answer 12

There are 18 groups in the periodic table

Question 13

What is Group 15 called

Answer 13

The Pnictogens

Question 14

What is group 16 called

Answer 14

The Chalogens

Question 15

What is group 1 called

Answer 15

The alkali metals

Question 16

What is group 3 called

Answer 16

The alkaline earth metals

Question 17

What are groups 3-12 called

Answer 17

The transition metals

Question 18

what is group 17 called

Answer 18

The halogens

Question 19

What is group 18 called

Answer 19

The noble gases

Question 20

What is the trend of reactivity as you go down Group 1

Answer 20

The reactivity increases as you go down the group

Question 21

Why does the reactivity increase as you go down group one

Answer 21

The atomic radius increases, so the force of attraction between the nucleus and electrons in the outer shell is weaker, therefore it looses its electrons to form ions more easily and is therefore more reactive.

Question 22

What is ionisation energy

Answer 22

It measures how easily and atom can lose electrons to form positive ions

Question 23

What is first ionisation energy

Answer 23

The energy required to remove one electron from each atom in one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions.

Question 24

What are the three factors affecting first ionisation energy

Answer 24

1. Atomic radius
2. Nuclear charge
3. Electron shielding

Question 25

Where is the first electron lost in an atom

Answer 25

It is lost from the highest energy level and therefore experiences the least attraction from the nucleus.

Question 26

How does atomic radius affect ionisation energy

Answer 26

The greater the distance from the nucleus and outer shell the less nuclear attraction from the nucleus. As the force of attraction decreases with increasing distance.

Question 27

How does nuclear charge affect first ionisation energy

Answer 27

The more protons there aer in the nucleus of an atom the greater the attraction between the nucleus and outer electrons.

Question 28

How does electron shielding affect ionisation energy

Answer 28

They are negatively charged, the inner-shell electrons repel the outer shell electrons. This repulsion leads to a shielding effect reducing the attraction.

Question 29

Which of the three factors has the greatest affect on ionisation energy

Answer 29

Atomic radius

Question 30

What is second ionisation energy

Answer 30

The energy required to remove one electron from each ion in one mole of gaseous 1+ ions of an element to form one mole of gaseous 2+ ions.

Question 31

Why is the second ionisation energy always greater than the first

Answer 31

Because more energy is required to remove the second electron as the nuclear charge increases as there are less electrons attracted to the same number of protons.