Topic 1: Key Concepts in Chemistry

Question 1

What is metallic bonding?

Answer 1

Attraction between positive metal ions and delocalised electrons in a lattice

Question 2

How does metallic bonding explain metal conductivity?

Answer 2

Delocalised electrons move freely carrying electric charge through metal

Question 3

How does metallic bonding explain malleability?

Answer 3

Layers of metal ions slide over each other without breaking bonds

Question 4

How does metallic bonding explain high melting points?

Answer 4

Strong electrostatic forces between ions and electrons need lots of energy to break

Question 5

What is a giant covalent structure?

Answer 5

A large 3D network of atoms joined by strong covalent bonds throughout

Question 6

Name three examples of giant covalent structures

Answer 6

Diamond Graphite Graphene

Question 7

Describe diamond’s structure

Answer 7

Each carbon atom bonded to four others in a rigid 3D tetrahedral lattice

Question 8

Properties of diamond

Answer 8

Very hard very high melting point does not conduct electricity insoluble in water

Question 9

Describe graphite’s structure

Answer 9

Layers of carbon atoms bonded to three others in hexagonal sheets with weak forces between layers

Question 10

Properties of graphite

Answer 10

Soft slippery high melting point conducts electricity along layers insoluble in water

Question 11

What is graphene?

Answer 11

A single layer of carbon atoms arranged in a hexagonal lattice

Question 12

Properties of graphene

Answer 12

Extremely strong conducts electricity very high melting point very thin and flexible

Question 13

What are fullerenes?

Answer 13

Molecules of carbon atoms arranged in hollow spheres or tubes

Question 14

Uses of fullerenes

Answer 14

Drug delivery catalysts lubricants electronics

Question 15

Properties of fullerenes

Answer 15

High surface area can trap molecules less strong than diamond or graphite

Question 16

What is covalent bonding?

Answer 16

Atoms share pairs of electrons forming strong bonds

Question 17

Properties of simple molecular substances

Answer 17

Low melting and boiling points weak intermolecular forces do not conduct electricity usually soluble in non-polar solvents

Question 18

What are giant covalent structures?

Answer 18

Substances with a huge network of covalently bonded atoms throughout structure

Question 19

Properties of giant covalent structures

Answer 19

Very high melting points insoluble do not conduct except graphite and graphene

Question 20

Define polymer

Answer 20

Large molecule made of repeating small units called monomers joined by covalent bonds

Question 21

Explain polymer chains

Answer 21

Long chains of covalently bonded carbon atoms with side groups attached

Question 22

Properties of ionic compounds

Answer 22

High melting and boiling points solid at room temperature brittle conduct electricity when molten or dissolved soluble in water but not in non-polar solvents

Question 23

Why are ionic compounds brittle?

Answer 23

Force applied shifts ions so that like charges repel causing structure to break

Question 24

What is ionic bonding?

Answer 24

Electrostatic attraction between positively charged cations and negatively charged anions

Question 25

How are group 1 ions formed?

Answer 25

Atoms lose one electron to form +1 ions

Question 26

How are group 2 ions formed?

Answer 26

Atoms lose two electrons to form +2 ions

Question 27

How are group 6 ions formed?

Answer 27

Atoms gain two electrons to form -2 ions

Question 28

How are group 7 ions formed?

Answer 28

Atoms gain one electron to form -1 ions

Question 29

What is a cation?

Answer 29

A positively charged ion formed by losing electrons

Question 30

What is an anion?

Answer 30

A negatively charged ion formed by gaining electrons

Question 31

What is electronic configuration?

Answer 31

The arrangement of electrons in shells around the nucleus of an atom

Question 32

How did Mendeleev arrange the periodic table?

Answer 32

By increasing atomic mass grouping elements with similar properties in columns

Question 33

What important decisions did Mendeleev make?

Answer 33

Left gaps for undiscovered elements switched order based on properties predicted properties of missing elements

Question 34

What was a limitation of Mendeleev’s table?

Answer 34

Some elements did not fit perfectly by atomic mass but he prioritized properties

Question 35

How is the modern periodic table arranged?

Answer 35

By increasing atomic number with elements grouped by similar chemical properties in columns called groups

Question 36

What defines a group in the periodic table?

Answer 36

Elements with the same number of electrons in outer shell

Question 37

What defines a period in the periodic table?

Answer 37

Elements with the same number of electron shells

Question 38

What is an isotope?

Answer 38

Atoms of the same element with same protons but different neutrons

Question 39

What is relative atomic mass?

Answer 39

Weighted average mass of an element’s isotopes compared to 1/12 mass of carbon-12

Question 40

What did Dalton propose about atoms?

Answer 40

Atoms are tiny solid spheres that cannot be divided

Question 41

What did Thomson propose?

Answer 41

Atoms are spheres of positive charge with electrons embedded like plum pudding

Question 42

What did Rutherford discover?

Answer 42

Atoms have a small dense positive nucleus with electrons orbiting outside

Question 43

Define mass number

Answer 43

Total number of protons and neutrons in an atom’s nucleus

Question 44

Define atomic number

Answer 44

Number of protons in an atom’s nucleus which defines the element