Sec 3 Chemistry Atomic Structure topical questions

Complete the particle table for a neutral atom of aluminium, A = 27, Z = 13.

State the relative charge and relative mass of the electron.

Write the electronic configuration of (a) nitrogen (Z = 7) and (b) potassium (Z = 19).

Chlorine-37 is written with A = 37, Z = 17. State the number of protons, neutrons and electrons in one neutral atom.

Define the two numbers used to label a nuclide.

1. (a)State what the proton number tells you.[1]
2. (b)State what the nucleon number tells you.[1]
3. (c)State which of the two decides the chemical identity of the atom.[1]

Complete the particle counts for each species.

1. (a)Give the electron count for the phosphorus atom.[1]
2. (b)Give the neutron and electron counts for the magnesium ion.[3]

Magnesium (Z = 12) reacts to form Mg²⁺.

1. (a)Write the electronic configurations of the Mg atom and the Mg²⁺ ion.[2]
2. (b)Explain why magnesium forms a 2+ ion rather than a 1+ ion.[2]

Bromine exists as 50.7% Br-79 and 49.3% Br-81.

1. (a)Calculate the relative atomic mass of bromine to 3 significant figures.[2]
2. (b)Explain why the value is close to 80 even though no bromine atom has mass 80.[2]

Complete the table for each particle.

Isotopes in medicine and archaeology: carbon-14 (A = 14) is radioactive and used for dating; carbon-12 is stable.

1. (a)State the number of neutrons in each isotope.[2]
2. (b)Explain why carbon-14 and carbon-12 have identical chemical properties.[2]
3. (c)State one physical property in which they differ slightly.[1]

A Chemistry data book lists magnesium as 79% Mg-24, 10% Mg-25 and 11% Mg-26. Treating these three as the sample’s composition, calculate the relative atomic mass of magnesium to 3 significant figures.

Silver exists as two isotopes: Ag-107 (51.8%) and Ag-109 (48.2%).

1. (a)Calculate the relative atomic mass of this sample of silver, giving your answer to one decimal place.[2]
2. (b)Explain why the answer is not exactly 108.[2]

Sulfur has the electronic configuration 2, 8, 6; calcium has 2, 8, 8, 2.

1. (a)Describe how a sulfur atom forms an ion, stating the ion’s configuration and charge.[2]
2. (b)Describe how a calcium atom forms an ion, stating the ion’s configuration and charge.[2]

Natural lithium is 6% Li-6 and 94% Li-7.

1. (a)Calculate the relative atomic mass of lithium, giving your answer to two decimal places.[2]
2. (b)Explain why the value is much closer to 7 than to 6.[2]
3. (c)State one physical property in which the two isotopes differ.[1]

Two particles have the configurations below.

1. (a)Identify the element each particle belongs to, and the charge on each.[4]
2. (b)State why P and Q do not react chemically in the same way despite both having full outer shells.[1]

Element R has two isotopes: R-63 (69.2%) and R-65 (30.8%).

1. (a)Calculate the relative atomic mass of R to 3 significant figures.[2]
2. (b)Identify element R using your value and the Periodic Table order of the first 36 elements.[1]
3. (c)Write the electronic configuration of the R⁺ ion.[2]

A student claims: "An O²⁻ ion, an O-18 atom and an O-16 atom are all just oxygen, so they must have identical masses and identical charges."

1. (a)Count protons, neutrons and electrons in each of the three particles (O: Z = 8).[4]
2. (b)Correct the student’s claim with one sentence that distinguishes isotopes from ions.[2]

An unknown element Q forms an ion, Q³⁺, which contains 10 electrons. A neutral atom of Q has a nucleon number of 27.

1. (a)Deduce the proton number of Q.[1]
2. (b)Deduce the number of neutrons in one atom of Q.[1]
3. (c)Write the electronic configuration of a neutral atom of Q.[1]
4. (d)State the group and period of Q in the Periodic Table, and name the element.[3]