Elements of life

Question 1

What are the subatomic particles in an atom and their charges?

Answer 1

Protons (+1), Neutrons (0), Electrons (-1).

Question 2

What is the relative mass of protons, neutrons, and electrons?

Answer 2

Protons and neutrons: 1, Electrons: 0.0005.

Question 3

What is the notation for an atom in terms of A, Z, and X?

Answer 3

A = Mass number, Z = Atomic number, X = Element symbol.

Question 4

What is Avogadro’s constant?

Answer 4

6.02 × 10²³ mol⁻¹.

Question 5

What are isotopes?

Answer 5

Atoms of the same element with different numbers of neutrons.

Question 6

What is the difference between cations and anions?

Answer 6

Cations are positively charged ions; anions are negatively charged ions.

Question 7

What is relative atomic mass (Ar)?

Answer 7

The mean relative mass of an atom compared to 1/12th of a carbon-12 atom.

Question 8

What is the equation for calculating moles from mass?

Answer 8

n = m / M, where n is moles, m is mass (g), and M is molar mass (g mol⁻¹).

Question 9

What is the molecular formula?

Answer 9

The actual number of atoms of each element in a molecule.

Question 10

What is the empirical formula?

Answer 10

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

Question 11

What is the formula for percentage yield?

Answer 11

Percentage yield = (Actual yield / Theoretical yield) × 100.

Question 12

What is water of crystallisation?

Answer 12

Water molecules embedded in a crystal structure.

Question 13

What is the formula for concentration in a solution?

Answer 13

n = c × V, where n is moles, c is concentration (mol dm⁻³), and V is volume (dm³).

Question 14

What is the use of a volumetric pipette?

Answer 14

To accurately measure a fixed volume of liquid.

Question 15

What is the use of a burette in titrations?

Answer 15

To dispense a solution and record its volume accurately.

Question 16

What is a standard solution?

Answer 16

A solution of known concentration.

Question 17

What is the equation for the first ionisation energy?

Answer 17

X(g) → X⁺(g) + e⁻.

Question 18

What is Hess’s law?

Answer 18

The enthalpy change of a reaction is independent of the path taken.

Question 19

What are sub-shells in electron configuration?

Answer 19

Divisions within electron shells, e.g., s, p, d, and f.

Question 20

What is the maximum number of electrons in the s, p, d, and f sub-shells?

Answer 20

s: 2, p: 6, d: 10, f: 14.

Question 21

What is the electronic configuration of sodium?

Answer 21

1s²2s²2p⁶3s¹.

Question 22

What is covalent bonding?

Answer 22

The sharing of electrons between two non-metal atoms.

Question 23

What is ionic bonding?

Answer 23

The transfer of electrons between a metal and a non-metal to form oppositely charged ions.

Question 24

What is metallic bonding?

Answer 24

The attraction between positive metal ions and a sea of delocalised electrons.

Question 25

What is the periodic trend for ionisation energy across a period?

Answer 25

Ionisation energy increases due to increasing nuclear charge and constant shielding.

Question 26

What is the trend in melting points across periods 2 and 3?

Answer 26

Melting points increase up to group 4, then decrease.

Question 27

What is nuclear fusion?

Answer 27

The process where two light atomic nuclei combine to form a heavier nucleus, releasing energy.

Question 28

What is the principle behind emission spectra?

Answer 28

Electrons absorb energy to jump to higher levels and emit photons when returning to lower levels.

Question 29

What are the flame test colours for common ions?

Answer 29

Li⁺: Bright red, Na⁺: Yellow, K⁺: Lilac, Ca²⁺: Dark red, Ba²⁺: Green, Cu²⁺: Blue-green.

Question 30

What is the equation for wave speed?

Answer 30

c = λ × ν, where c is wave speed, λ is wavelength, and ν is frequency.

Question 31

What is the formula for calculating relative atomic mass from a mass spectrum?

Answer 31

Relative atomic mass = (Σ(relative isotopic mass × abundance)) / 100.

Question 32

What is a salt?

Answer 32

A compound formed when the hydrogen in an acid is replaced by a metal or ammonium ion.

Question 33

What is the general reaction for acids and carbonates?

Answer 33

Acid + Carbonate → Salt + Water + Carbon Dioxide.

Question 34

What is a precipitation reaction?

Answer 34

A reaction where an insoluble solid (precipitate) forms in solution.

Question 35

What is the test for ammonium ions (NH₄⁺)?

Answer 35

Add sodium hydroxide and heat; test for ammonia gas with damp red litmus paper, which turns blue.

Question 36

What is the test for halides (Cl⁻, Br⁻, I⁻)?

Answer 36

Add nitric acid and silver nitrate: Cl⁻ forms white precipitate, Br⁻ cream, I⁻ yellow.

Question 37

What is the trend in solubility of group 2 hydroxides?

Answer 37

Solubility increases down the group.

Question 38

What are group 2 carbonates?

Answer 38

Compounds with the formula MCO₃ that decompose into metal oxides and CO₂ upon heating.

Question 39

What is charge density?

Answer 39

The concentration of charge on a cation, affected by ionic size and charge.

Question 40

What is Bohr's model of the atom?

Answer 40

Electrons orbit the nucleus in fixed energy levels, with energy levels converging at higher values.

Question 41

What are the periodic table groups?

Answer 41

Columns of elements with the same number of outer shell electrons.

Question 42

What is the importance of the periodic table periods?

Answer 42

Rows that indicate the number of electron shells in elements.

Question 43

What are noble gases?

Answer 43

Unreactive elements in group 18 with full outer electron shells.