Foundations in chemistry

Question 1

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

Answer 1

• Proton = +1
• Electron = 0
• Neutron = -1

Question 2

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

Answer 2

• Proton = 1
• Electron = 1/1840
• Neutron = 1

Question 3

What is meant by the term molecular formula?

Answer 3

Number of atoms of each element

Question 4

What is meant by the term empirical formula?

Answer 4

Simplest whole number ratio of atoms

Question 5

What is meant by the term relative atomic mass?

Answer 5

Weighted mean mass of an atom compared with 1/12th mass of carbon-12

Question 6

What is meant by the term relative isotopic mass?

Answer 6

Mass of the isotope compared to 1/12th carbon-12

Question 7

What are isotopes?

Answer 7

Atoms of an element with different number of neutrons

Question 8

State the similarities and differences between the atomic structure of isotopes of the same element

Answer 8

• Similarities = same number of protons and electrons
• Differences = different number of neutrons, physical properties and atomic masses

Question 9

What is a polyatomic ion?

Answer 9

Contains more than one atom

Question 10

What are examples of polyatomic ions and ions?

Answer 10

• Polyatomic ions = NO3-, SO42-, CO32-, OH-, NH4+
• Ions = Zn2+, Ag+

Question 11

What is meant by an orbital?

Answer 11

A region within an atom that can hold up to two electrons with opposite spin

Question 12

What is the shape of a s-orbital and p-orbital?

Answer 12

• S-orbital = spherical
• P-orbital = dumb-bell shape

Question 13

What term is given to the ‘.xH2O’ part of a formula?

Answer 13

Water of crystallisation

Question 14

What is meant by anhydrous?

Answer 14

Without water of crystallisation

Question 15

What is meant by an alkali?

Answer 15

Releases OH-

Question 16

What is meant by an acid?

Answer 16

A proton donor

Question 17

Why might something act as a base?

Answer 17

Accepts a proton/H+

Question 18

What is meant by a salt?

Answer 18

When the H+ in an acid is replaced by a metal ion

Question 19

What is meant by a standard solution?

Answer 19

A solution of known concentration

Question 20

What is a weak acid?

Answer 20

Partially dissociates/ionises

Question 21

What is a strong acid?

Answer 21

Fully dissociates/ionises

Question 22

State the important uses of the compound (NH4)2SO4/ammonia

Answer 22

• Fertiliser
• Manufacture of explosives and dyes

Question 23

What is the ionic equation for a neutralisation reaction?

Answer 23

H+(aq) + OH-(aq) -> H2O(l)

Question 24

What are examples of equations for the reaction of bases?

Answer 24

• Acid + metal carbonate -> salt + water + carbon dioxide
• Acid + metal oxide -> salt + water

Question 25

What is an example of an equation for redox reactions with metals?

Answer 25

Metal + acid -> salt + hydrogen

Question 26

What is meant by disproportionation?

Answer 26

Oxidation and reduction of the same element

Question 27

1) What is Avogadro's constant? 2) How can you find the number of moles using this? 3) How can you find the number of particles using this?

Answer 27

1) 6.02 x 10^23 2) Number of particles you have/number of particles in a mole 3) Moles x Avogadro's constant

Question 28

What is the ideal gas equation?

Answer 28

- pV = nRT - p = Pa - V = m3 - R = 8.314 - T = K

Question 29

How can you find the gas volume?

Answer 29

Number of moles = volume in dm3/cm3 divided by 24/24000

Question 30

How can you find the number of moles?

Answer 30

- Mass = Mr x moles - Moles = concentration x volume (dm3)

Question 31

What is meant by an ionic bond?

Answer 31

Electrostatic attraction between oppositely charged ions

Question 32

What is meant by an ionic lattice?

Answer 32

Repeating pattern of oppositely charged ions

Question 33

What is meant by a covalent bond?

Answer 33

A shared pair of electrons

Question 34

What is meant by a dative covalent (coordinate) bond?

Answer 34

Both electrons have been donated by one atom

Question 35

What is meant by electronegativity?

Answer 35

The ability of an atom to attract electrons

Question 36

Why might a molecule be polar?

Answer 36

- The dipoles do not cancel out because the molecule is non-symmetrical - There is a difference in electronegativities

Question 37

Describe how London forces arise?

Answer 37

- Uneven distribution of electrons - Creates a temporary dipole in a molecule - Causes induced dipoles in neighbouring molecules

Question 38

State and explain two anomalous properties of ice caused by hydrogen bonding

Answer 38

- Ice is less dense than water. The molecules in ice are held far apart by hydrogen bonds - Ice has a relatively high melting point. Hydrogen bonds are relatively strong

Question 39

Explain the tend of the melting points of aluminium, silicon and phosphorous in period 3

Answer 39

- Al has metallic bonding - Si has covalent bonding - P has London forces between molecules - Al and Si are giant - P is simple molecular - Metallic and covalent are stronger than London forces