7.3 Periodic trends in bonding and structure

Question 1

What are semi-metals or metalloids

Answer 1

Elements near to the metal/non-metal divide

Cahn show in-between properties

Question 2

At room temperature, all metals except mercury are…

Answer 2

…solids

Question 3

Common property among all metals

Answer 3

Ability to conduct electricity

Question 4

What bonding takes place in a metal

Answer 4

Metallic bonding

Question 5

What is metallic bonding

Answer 5

The strong electrostatic attraction between cations and delocalised electrons

Question 6

In a solid metal structure, each atom has donated its ______ outer-shell ______ to a shared pool of ______ which are ______ throughout the whole structure. The ______ left behind consist of the ______ and the inner ______ ______ of the metal atoms

Answer 6

Negative
Electrons
Electrons
Delocalised
Cations
Nucleus
Electron shells

Question 7

Cations in metallic bonding

Answer 7

They are fixed in position, maintaining the structure and shape of the metal

Question 8

Electrons in metallic bonding

Answer 8

The delocalised electrons are mobile and are able to move throughout the structure. Only the electrons move

Question 9

In a metal structure, billions of metal atoms are held together by metallic bonding in a…

Answer 9

Giant metallic lattice

Question 10

Most metals have:

Answer 10

Strong metallic bonds - attraction between positive ions and delocalised electrons
High electrical conductivity
High melting and boiling points

Question 11

In what states do metals conduct electricity

Answer 11

Solid or Liquid

Question 12

What happens when a voltage is applied across a metal

Answer 12

The delocalised electrons can move through the structure, carrying charge

Question 13

Why can’t ionic compounds conduct electricity when solid

Answer 13

They have no mobile charge carriers in this state

Question 14

Why is Tungsten used in the filaments of halogen lamps

Answer 14

It has the highest melting point, other metals would melt

Question 15

What does the melting point of a metal depend on

Answer 15

The strength of the metallic bonds holding together the atoms in the giant metallic lattice

Question 16

For most metals ______ temperatures are necessary to provide the ______ amount of energy needed to ______ the ______ ______ attraction between the cations and electrons

Answer 16

High
Large
Overcome
Strong Electrostatic

Question 17

Why do most metals have a high melting and boiling point

Answer 17

The strong electrostatic attraction between the cations and electrons

Question 18

Do metals dissolve

Answer 18

No

Question 19

Many simple non-metallic molecules form a ______ ______ ______ structure and have ______ melting and boiling points due to ______ intermolecular forces

Answer 19

Simple Molecular Lattice
Low
Weak

Question 20

What do non-metals such as boron, carbon and silicon form

Answer 20

A giant covalent lattice

Question 21

Structure of diamond

Answer 21

Tetrahedral arrangement of atoms in the diamond form of carbon
Bond angles are all 109.5 by electron-pair repulsion
The dot and cross diagram shows part of covalently bonded network of carbon atoms

Question 22

Melting and boiling points of substances with a giant covalent lattice structure

Answer 22

High melting and boiling points
Because covalent bonds are strong
High temperatures necessary to provide large quantity of energy needed to break the strong covalent bonds

Question 23

Solubility of substances with a giant covalent lattice structure

Answer 23

Insoluble in almost all solvents
The covalent bonds holding together the atoms in the lattice are far too strong to be broken by interaction with solvents

Question 24

Electrical conductivity

Answer 24

Giant covalent lattices are non-conductors of electricity

The only exceptions are graphene and graphite

Question 25

Electrical conductivity and carbon (diamond) and silicon

Answer 25

All four outer shell electrons are involved in covalent bonding so none are available for conducting electricity

Question 26

Why can carbon conduct electricity

Answer 26

Forms several structures in which one is available for conductivity. Graphene and graphite both conduct electricity

Question 27

What is graphene

Answer 27

A single layer of graphite

Hexagonally arranged carbon atoms linked by strong covalent bonds

Question 28

What is graphite

Answer 28

Composed of parallel layers of hexagonally arranged carbon atoms
Layers are bonded by weak London forces
Only uses three of carbon’s four outer shell electrons

Question 29

Periodic trend in melting points

Answer 29

Across period 2 and 3,
The melting point increases from group 1 to group 14
There is a sharp decrease in melting point between Group 14 and 15
The melting points are comparatively low from group 15 to 18