2 Atoms, Ions, and Compounds

Question 1

Describe how elements are ordered in the periodic table.

Answer 1

The periodic table lists elements in order of the number of protons in the nucleus. This is the atomic number and is unique to each element.

Question 2

Define isotopes. Explain why they different physical properties but the same chemical reactivities.

Answer 2

Different isotopes of the same element have the same number of protons and electrons, but different numbers of neutrons. This results in different masses which can change the physical properties slightly. Chemical reactivities are identical as they have the same electron structures.

Question 3

Define relative isotopic mass.

Answer 3

Relative isotopic mass is the mass of an isotope relative to 1/12^th of the mass of an atom of carbon-12.

Relative isotopic mass has no units because it is a ratio of two masses.

Question 4

Define relative atomic mass.

Answer 4

Relative atomic mass is the weighted mean mass of an atom of an element relative to 1/12^th of the mass of an atom of carbon-12.

Question 5

What is the basis of how ions are separated in a mass spectrometer?

Answer 5

Ions are accelerated and deflected. Heavier ions deflect less than lighter ones and they separate out on the basis of their mass.

The ions are detected as a mass-to-charge ratio (m/z).

Question 6

State the formula for nitrate ions.

Answer 6

NO₃^-

Question 7

State the formula for nitrite ions.

Answer 7

NO₂^-

Question 8

State the formula for hydrogencarbonate.

Answer 8

HCO₃^-

Question 9

State the formula for manganate (VII).

(also known as permanganate)

Answer 9

MnO₄^-

Question 10

State the formula for carbonate ions.

Answer 10

CO₃^2-

Question 11

State the formula for sulfate ions.

Answer 11

SO₄^2-

Question 12

State the formula for sulfite ions.

Answer 12

SO₃^2-

Question 13

State the formula for dichromate (VI).

Answer 13

Cr₂O₇^2-

Question 14

State the formula for the phosphate ion.

Answer 14

PO₄^3-

Question 15

Write the equation for magnesium reacting with oxygen.

Answer 15

2 Mg_(s) + O_2(g) ⇒ 2 MgO_(s)

Question 16

Write the equation for sodium reacting with excess water.

Answer 16

2 Na_(s) + 2 H₂O_(l) ⇒ 2 NaOH_(aq) + H_2(g)

Question 17

Write the equation for magnesium reacting with hydrochloric acid.

Answer 17

Mg_(s) + 2 HCl_(aq) ⇒ MgCl_2(aq) + H_2(g)

Question 18

Write an equation for magnesium oxide reacting with nitric acid.

Answer 18

MgO_(s) + 2 HNO_3(aq) ⇒ Mg(NO₃)_2(aq) + H₂O_(l)

Question 19

Write an equation for the neutralisation of sodium hydroxide with sulfuric acid.

Answer 19

2 NaOH_(aq) + H₂SO_4(aq) ⇒ Na₂SO_4(aq) + H₂O_(l)

Question 20

Write the equation for the neutralisation of hydrochloric acid with copper carbonate.

Answer 20

CuCO_3(s) + 2 HCl_(aq) ⇒ CuCl_2(aq) + H₂O + CO_2(g)

Question 21

Write an equation for the neutralisation reaction between ammonia and hydrochloric acid.

Answer 21

NH_3(aq) + HCl_(aq) ⇒ NH₄Cl_(aq)

Question 22

How do you decide how many figues to include in your final answer?

Answer 22

Look at all the figures given in the question. The one with the fewest significant figures gives you the number of significant figures to use as they should be the same.