Bonding

Question 1

What is a cation?

Answer 1

A positive ion

Question 2

What is an anion?

Answer 2

A negative ion

Question 3

What is an ionic bond?

Answer 3

When positive and negative ions are held together strongly by electrostatic forces of attraction in a giant lattice structure.

Question 4

What is the explanation for why an ionic substance has a high melting and boiling point?

Answer 4

The electrostatic forces of attraction between cations and anions are strong in a giant lattice, requires a lot of energy to overcome

Question 5

What is the explanation for why ionic substances are hard but brittle?

Answer 5

Because they have strong bonds between the positive and negative ions, BUT if the lattice distorts the ions repel and the structure breaks

Question 6

What is the explanation for why ionic substances are generally soluble in water?

Answer 6

Water is polar so the ions are attracted to it

Question 7

What is the explanation for why ionic substances don’t conduct electricity in the solid state?

Answer 7

The charged particles (ions) cannot move

Question 8

What is the explanation for why ionic substances conduct electricity as liquids?

Answer 8

The ions are free to move

Question 9

What happens when metals react with non metals?

Answer 9

1) the metal atoms lose electrons
2) the non metal atoms gain electrons
3) an ionic compound is made

Question 10

EXAMPLE QUESTION:
magnesium oxide has a higher melting point than sodium chloride - explain why this is the case

Answer 10

Stronger bonds - the attraction between Mg and O is stronger in bigger charges due to larger electrostatic charges - more electrons have been exchanged

Question 11

differences between simple covalent and giant covalent;

Answer 11

Simple; composed molecules - contain several atoms bonded strongly together by covalent bonds
Giant; contain million of atoms bonded by many strong covalent bonds to form a giant lattice

Question 12

are the IMF of covalent bonds strong or weak?

Answer 12

weak IMF between molecules - little energy needed to overcome

Question 13

are the bonds of covalent bonds strong or weak?

Answer 13

strong - lots of energy is needed to break them

Question 14

What is the explanation for why covalent substances have low melting and boiling points and why many are liquid or a gas at room temperature?

Answer 14

IMF are weak so little energy is needed to separate electrons

Question 15

What is the explanation for why covalent substances have poor electrical conductivity?

Answer 15

no charged particles to move

Question 16

What is the explanation for why covalent substances have poor solubility in water?

Answer 16

no charges so no attraction to polar water

Question 17

what is a covalent bond?

Answer 17

strong electrostatic forces of attraction between two nuclei and a shared pair of electrons

Question 18

Why do diamond and graphite have different physical properties?

Answer 18

in diamond each C is bonded to 4 other carbons, in graphite only 3

Question 19

description of a diamond structure;

Answer 19

each C atom is joined to 4 others by strong covalent bonds throughout the whole structure

Question 20

description of a graphite structure;

Answer 20

each C atom is joined to 3 others within a layer, strong covalent bonds throughout a layer, weak intermolecular forces between layers

Question 21

are diamond structures hard?

Answer 21

very hard - bonds are strong in all directions

Question 22

are graphite structures hard?

Answer 22

soft between the layers as the IMF are weak

Question 23

Diamond electrical conductivity?

Answer 23

none - no charges no ions

Question 24

graphite electrical conductivity?

Answer 24

good conductor - delocalised electrons

Question 25

Why do diamond and graphite have high melting point?

Answer 25

because diamonds have strong bonds in all directions and graphite has strong bonds in the layers, takes a lot of energy to break strong bonds

Question 26

what are atoms in metals held together by?

Answer 26

metallic bonds

Question 27

Explanation for why metallic bonds have high melting and boiling points?

Answer 27

because strong electrostatic forces between cations and delocalised electrons need lots of energy to break

Question 28

Explanation for why metallic bonds are malleable and ductile?

Answer 28

layers of ions can slide over eachother

Question 29

Explanation for why metallic bonds are good conductors of electricity?

Answer 29

delocalised electrons are able to move

Question 30

Explanation for why metallic bonds are good conductors of heat?

Answer 30

because delocalised electrons carry kinetic energy through the lattice

Question 31

What are alloys?

Answer 31

mixtures of metals where the different metals are metallically bonded in a giant metal lattice

Question 32

why aren’t alloys regarded as compounds?

Answer 32

they don’t have a specific ratio and can be separated by physical means. Elements in an alloy react how the separate elements react