Bonding+Structure

Question 1

What happens when metals form ions

Answer 1

They lose electrons from their outer shell to form a positive ion

Question 2

What happens when non-metals form ions

Answer 2

They gain electrons from their outer shell to from a negative ion

Question 3

Cation

Answer 3

Positive ion

Question 4

Anion

Answer 4

Negative ion

Question 5

What happens when a metal and non-metal react together

Answer 5

Metal loses electrons to form a positively charged ion and the non-metal gains these electrons to form a negatively charged ion

Question 6

Force between an ionic bond

Answer 6

Electrostatic forces

Question 7

What is an ionic bond

Answer 7

When a metal and non-metal react together

Question 8

Negatives of a dot cross diagram

Answer 8

• don’t show the structure of the compound
• doesn’t show size of ions
• doesn’t show how they’re arranged

Question 9

What diagram is used to show an ionic bond

Answer 9

Dot cross diagram

Question 10

Structure of an ionic compound

Answer 10

Giant ionic lattice

Question 11

Formation of ionic lattice

Answer 11

-closely packed
-strong electrostatic forces of attraction between oppositely charged ions in all directions of lattice

Question 12

Properties of ionic compounds

Answer 12

-high melting and boiling point due to strong bonds between ions. Takes a lot of energy to overcome attraction
-when solid, they can’t conduct electricity because the ions are held in place
-when ions melt, they’re free to move and they’ll carry electric charge
-some ionic compounds dissolve in water so ions separate and are all free to move in the solution so they’ll carry electric charge

Question 13

What is a covalent bond

Answer 13

Where atoms share electrons with eachother so that they’ve got full outer shells

Question 14

What elements use covalent bonding

Answer 14

Non-metal atoms and compounds

Question 15

Displayed formula

Answer 15

Only lines (1 line=1 bond, 2 lines=2bonds)

Question 16

Diagram for covalent bonds

Answer 16

Dot cross, over lapping lines, shared electrons

Question 17

What bonds are formed in simple molecular substances

Answer 17

Covalent

Question 18

Strength of simple molecular structures

Answer 18

-atoms held together with very strong covalent bonds
-intermolecular forces are very weak

Question 19

Properties of simple molecular structures

Answer 19

-low melting + boiling points (weak intermolecular forces)
-most molecular substances are gases or liquids at room temperature
-as molecules get bigger so do the intermolecular forces so more energy is needed to break them
-don’t conduct electricity, they just aren’t charged so no free electrons or ions

Question 20

Polymer

Answer 20

Lots of small units linked together to form a long molecule that has repeating sections.

Question 21

Bonds in a polymer

Answer 21

Covalent

Question 22

Intermolecular forces of polymers

Answer 22

-very large so more energy is needed to break them. Usually solid at room temperature
-still weaker than ionic or covalent bonds so they have lower melting and boiling points than ionic or giant molecular compounds

Question 23

Properties of giant covalent structures

Answer 23

-all atoms bonded to eachother by strong covalent bonds
-high melting a boiling points (lots of energy needed to break)
-don’t contain charged particles so they don’t conduct electricity not even when molten (except for graphite)

Question 24

Main examples of giant covalent structure

Answer 24

Diamond
Graphite
Silicon dioxide

Question 25

Silicon dioxide

Answer 25

-silica -what sand is made of -each grain of sand is one giant structure of silicon and oxygen

Question 26

What is an allotrope

Answer 26

Different structural forms of the same element in the same physical state

Question 27

Diamond

Answer 27

-giant covalent structure made up of carbon atoms -each carbon atom has 4 covalent bonds which makes diamond really hard -high melting point (string covalent bonds which need a lot if energy to break) -doesn’t conduct electricity (no free electrons or ions)

Question 28

Graphite

Answer 28

-each carbon atoms forms 3 covalent bonds -has one free delocalised electron: so it conducts electricity and thermal energy -sheets of carbon atoms arranged in hexagons -weak forces between layers so they can move over eachother freely -this makes graphite soft and slippery: ideal lubricating material

Question 29

Graphene

Answer 29

-one layer of graphite -one atom thick -very light: can be added to composite materials to improve their strength without adding much weight -also contains delocalised electrons so can conduct electricity through whole structure -has the potential to be used in electronics

Question 30

What are fullerenes

Answer 30

Molecules of carbon, shaped like closed tubes or hollow balls

Question 31

Formation of fullerenes

Answer 31

-made up of carbon atoms formed in hexagons (or pentagons or heptagons) -huge surface area- help make great industrial catalysts

Question 32

Uses of fullerenes

Answer 32

-can ‘cage’ other molecules, to deliver drugs into body -can make great industrial catalysts -can be good lubricants

Question 33

Nanotubes

Answer 33

-formed by fullerenes in cylinders -can conduct electricity and thermal energy -high tensile strength (don’t break when stretched) -very high ratio between length and diameter

Question 34

Functions of nanotubes

Answer 34

-used in nanotechnology -can be used in electronics or to strengthen materials without adding much weight such as tennis racket frames

Question 35

What happens in metallic bonding

Answer 35

-electrons of outer shell of metal atoms are delocalised -strong forces of electrostatic attraction between positive metal ions and negative electrons -these forces of attraction hold the atoms together in a regular structure known as metallic bonding. It’s very strong

Question 36

Properties of metals

Answer 36

-solid at room temp: strong electrostatic forces (high melt/boil points) -good conductors of electricity and heat: delocalised electrons carry charge through whole structure -malleable: layers of atoms can slide over eachother

Question 37

Alloys

Answer 37

-harder than pure metals -mixture of 2 or more metals -pure metals can be too soft -when different atoms mix, the atoms are different sizes so it’s harder for them to slide over eachother, so they’re harder