Core Concepts

Question 1

What is an atom?

Answer 1

An atom is the smallest part of an element that still has its chemical properties.

Question 2

What is a molecule?

Answer 2

A molecule consists of two or more atoms chemically joined together.

Question 3

What is an element?

Answer 3

An element is a substance made from atoms with the same number of protons in its nucleus (the same type of atom).

Question 4

What is a compound?

Answer 4

A compound consists of two or more elements chemically joined together

Question 5

Give the meaning of the term ion?

Answer 5

An ion is a charged particle formed when an atom, or group of atoms, loses or gains electrons. (Cations - loses) (Anions - gains)

Question 6

From 1803 - 1932, who were the seven men that contributed to the atomic structure?

Answer 6

• Dalton
• Thomson
• Rutherford
• Bohr
• Chadwick

Question 7

What did Dalton think?

Answer 7

• All atoms of an element were identical
• atoms had different elements
• The solid atom model

Question 8

What did Thomson think/discover?

Answer 8

• Discovered the electron
• The plum pudding model (Atoms are spheres of positive charge with negative electrons dotted around inside them)

Question 9

What did Rutherford discover/think?

Answer 9

• The solar system model (Atoms have a positive nucleus surrounded by negative electrons in orbit)
• [after Bohr] Rutherford then discovers the proton

Question 10

What did Bohr think/discover?

Answer 10

• The electron shell model (electrons occupy shells or energy levels around the nucleus)

Question 11

What did Chadwick discover?

Answer 11

• The neutron

Question 12

What is the relative charge and relative mass of a proton, neutron and electron?

Answer 12

Element ~ relative charge ~ mass
Proton ~ +1 ~ 1
Neutron ~ 0 ~ 1
Electron ~ -1 ~ 1/1836

Question 13

What is an isotope?

Answer 13

Isotopes are atoms of an element with the same number of protons but different numbers of neutrons

Question 14

What is the atomic number?

Answer 14

It is the lower digit, it is the number of protons in the nucleus and is the atoms position on the table.

Question 15

What is the structure of ionic compounds?

Answer 15

They are in a lattice
- regular arrangements of ions
- Ionic binds between oppositely

Question 16

What are ionic bonds?

Answer 16

Ionic bonds are strong electrostatic forced between oppositely charged ions. Between metals and non-metals.

Question 17

How do you Draw a dot and cross diagram for ionic bonding?

Answer 17

You add them then use square brackets and add the electrons and charges

Question 18

What melting and boiling points do ionic compounds have?

Answer 18

High!
Solid at room temperature.
The bonds are strong so require more energy to break.

Question 19

Are ionic compounds soluble in water?

Answer 19

They are often soluble in water

Question 20

When does covalent bonding occur?

Answer 20

A covalent bond formed when a pair of electrons is shared between two atoms. (Between non-metals)

Question 21

What are the properties of covalent bonds?

Answer 21

• strong
• form between non-metal atoms

Question 22

What are simple molecular substances?

Answer 22

A simple molecule consists of just a few atoms, joined to eachother by strong covalent bonds.
- Low melting and boiling points
Usually gas or liquid at room temperature
- they do not conduct electricity (not electrically charged and do not contain free electrons)
- Simple molecular bonds dissolve in water but as insoluble

Question 23

Simple molecular substances

Answer 23

Due to the weak attractive forces between molecules (intermolecular forces) - the intermolecular break but not the covalent

Question 24

Properties of Diamond

Answer 24

• Each atom is bonded to four others
• Strong covalent bonds between atoms
• Giant molecular substance
• Does not conduct electricity

Question 25

Graphine properties

Answer 25

- Each atom is bonded to three others - Weak intermolecular forces between layers - Strong covalent bonds between atoms in a layer

Question 26

Graphite is used to make electrodes because it conducts electricity. Explain why it conducts but diamond does not. [4marks]

Answer 26

A carbon atom can form four covalent, in graphite each carbon only has three bonds. The non-bonding outer electron becomes delocolised. Meaning it can pass through the structure, so graphite can co duct electricity. Diamond does not have this because all four bonds are made.

Question 27

What is Graphene?

Answer 27

- (singular sheet of graphite) - A giant molecular substances. - It has a regar lattice structure - The non-bonding outer electrons become delocolised - Graphene is very strong and flexible - Strong covalent bonds - Its layers are once atom thick

Question 28

What is Buckminsterfullerene?

Answer 28

- C(60) - has carbon atoms arranged in Pentagon's as well as hexagons - Condict electricity because of the delocolised electrons - Are soft when in solid state because they have weak intermolecular forces

Question 29

Metal properties and bonds

Answer 29

- Consists of a giant a gaint lattice of positively charged metal ions - has a "sea" of delocolised electrons - Insoluble in water but some might dissolve - Metalic bonds are strong electrostatic forces of attraction between positive metal ions and delocalised electrons

Question 30

What is the Empirical formulae

Answer 30

The simplest whole number ratio of atoms of atoms of each element in compound.