Chapter 7

Question 1

Mendeleev

Answer 1

Arranged elements in order of atomic mass
Aligned elements in groups with similar properties
Swapped elements and left gaps
Predicted the properties of missing elements

Question 2

What is a group

Answer 2

The elements are arranged in vertical columns

Same number of outer shell electrons

Question 3

What is a period

Answer 3

The elements are arranged in horizontal rows

Number of the highest energy electron shell in the elements atom

Question 4

Periodicity

Answer 4

A repeating trend in properties of the elements across each period

Question 5

Trends across a period

Answer 5

Each period starts with an electron in a new highest energy shell

S subshell fills with 2 electrons
P fills with 6

Group 4
3D subshell fills with 5

Question 6

Trends down a group

Answer 6

Elements in each group have atoms with the same number of electrons in each sub shell

Same chemical properties

Question 7

Blocks

Answer 7

Divides elements corresponding to their highest energy sub shell

Question 8

Ionisation energy

Answer 8

Measures how easily an atom loses electrons to form positive ions

Question 9

First ionisation energy

Answer 9

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 10

Factors that affect ionisation energy

Attraction between the nucleus and the outer electrons of an atom

Answer 10

Atomic radius
Electron shielding
Nuclear charge

Question 11

Atomic radius

Answer 11

The greater the distance
between the nucleus and outer electrons
the less the nuclear attraction
the easier it is to lose an electron

Question 12

Nuclear charge

Answer 12

The more protons there are
Te greater the attraction between the nucleus and outer electrons
Harder to lose electrons

Question 13

Electron shielding

Answer 13

Inner shell electrons repel outer shell electrons = shielding effect

Reduces the attraction between the nucleus and outer electrons

Question 14

Why is the second ionisation energy is greater than the first

Answer 14

Removed from positive ion, more protons than electron
Greater pull on electrons from nucleus
Less shielding and repulsion from other electrons so held more closely

Large jump in ionisation energy across shells because - less shielding

Question 15

What predictions can you make from successive ionisation energies

Answer 15

The number of electrons in the outer shell

The group of the element

The identity of the element

Question 16

Trends in first ionisation energies of elements across a period

Answer 16

General increase in first ionisation energy

Sharp decrease between the end of one period and the start of another

Question 17

Trend in first ionisation energy down a group

Answer 17

FIE decreases down a group

Atomic radius increases
Shielding increased
Nuclear attraction on outer electrons decreases

Question 18

Trend in first ionisation energy across a period

Answer 18

General increase of FIE

Nuclear charge increases
Same shell - same shielding
Nuclear radius decreases
Nuclear attraction increases

Question 19

Subshell trends in first ionisation energy

First drop - 2,3

Answer 19

The start of filling the 2p subshell

2p subshell in boron has a higher energy than the 2s subshell in beryllium
Therefore 2p electron is easier to remove than one of the 2s electrons in beryllium

Question 20

Why does FIE rise and fall across a period

Answer 20

Due to the existence of subshells, their energies, and how they fill with electrons

Question 21

Subshell trends in first ionisation energy

Second drop - 5,6

Answer 21

Phosphorous has 3 electrons in the 3p subshell (1 in each)
Sulfur has 4 electrons in the 3p subshell (2 paired in one orbital, 1 in each of the other 2)
The paired electrons in sulfur repel each other
Making it easier to remove one of these electrons than an unpaired one

Question 22

Metalloids

Answer 22

Elements near the metal/non metal divide

Question 23

Metallic bonding and structure

Answer 23

Strong electrostatic attraction between positive cations and negative delocalised electrons

Billions of metal atoms held by metallic bonding to form giant metallic lattices

Question 24

Properties of metals

Answer 24

Strong metallic bonds
High electrical conductivity
High mp bp

Question 25

Properties of giant covalent lattice structures

Answer 25

High mp,bp

Insoluble - covalent bonds can’t be broken by interactions with solvents

Electrical conductivity - none except graphene and graphite

Question 26

Graphene and graphite

Answer 26

Carbon based on planar hexagonal layers - 120

Each carbon only forms 3 bonds
Spare electrons are delocalised

Question 27

Periodic trend in melting points

Answer 27

Melting point increases from 1-14
As metallic bonds get stronger
Because metallic ions have an increasing positive charge, more delocalised electrons, smaller atomic radius

Giant covalent lattices
Structure made of strong covalent bonds that link atoms together
A lot of energy needed to break these bonds

Molecular substances
Mp depends on strength of London forces
London forces are weak
Larger atoms with more electrons have stronger London forces

Argon is low because monoatomic

Question 28

Allotrope

Answer 28

Different forms of the same element in the same

Question 29

Structure of graphite

Answer 29

Carbons arranged in sheets of hexagons
Each carbon covalently bonded to 3 other carbons
4th outer electron is delocalised
Layers of sheets held together by London forces

Question 30

Similarity and differences between first ionisation across period 2 and 3

Answer 30

Similar

Same trend
Because similar subshell structure across period

Difference
Period 3 would have lower ionisation values
Because electrons are further away from nucleus and experience more shielding