Mod 2A: ElectronsRE Testanswers/27%

1)This question is about two elements, A and B, in the periodic table.

a)Each atom of element A has 16 electrons.

i)Identify element A.[1]

Sulpher

ii)Complete the electronic configuration of A.[1]

1s22s2 2p6 3s2 3p4

iii)Predict the charge on an ion of A and complete its electronic configuration.[2]

Charge on ion __2-___electronic configuration of ion of A 1s22s2 2p6 3s2 3p6

Allow transferred errors from charge to configuration.

b)Element B exists as a mixture of three isotopes.

The atoms of element B have five electrons in the 3d sub – shell. Identify element B.[1] Mn

c)How many orbitals does the 3d sub shell have? [1]5

d)What is meant by the term orbital? [3]It is a region within an atom that hold up to 2 electrons with opposite spins

2)The Group 7 element chlorine is obtained from the electrolysis of brine. It is used in bleaches and disinfectants.

a)The electronic configuration of a chlorine atom can be written in terms of sub – shells.

i)Complete the electronic configuration of a chlorine atom. [2]

1s22s22p63s23p5 (2) 1 mark for p5 if incorrect

ii)Why is chlorine classified as a p – block element? [1]

Outer electrons are in a p sub shell / orbital / shell

3)The first six ionisation energies of an element D are shown in the table.

1st / 2nd / 3rd / 4th / 5th / 6th
1086 / 2353 / 4621 / 6223 / 37832 / 47278

a)Define the term first ionisation energy. [3]

The energy change when each atom in one mole (1) of gaseous atoms (1) Loses an electron (1) to form one mole of gaseous 1+ ions.

Or

1 Mole of gaseous atoms loses 1 mole of electrons3 marks

Or

D(g)D+(g)+e-2 marks

Or

D(g)D+(g)+e-H / IE = ….. KjMol-13 marks

b)Write an equation, including state symbols, to represent the second ionisation energy of element D.[2]

D1+(g)D2+(g)+e-(1)– equation(1) – state symbols

Can use any example or letter instead of D, ‘-‘ not required on electron

c)Use the table to deduce which group of the Periodic Table contains element D.[3]

Group ___4____

Explanation

Sharp rise in successive ionisation energy between 4th and 5th IE (1)

Which marks a change to a new shell / energy level / 4e in outer shell (1)

***Mention of – orbital / sub shell cancels mark 2.

4)This question is about gallium oxide, Ga2O3.

a)Successive ionisation energies provide evidence for the arrangement of electrons in atoms. The graph below shows the 8 successive ionisation energies for oxygen.

i)Write an equation, including state symbols, to represent the fourthionisation energy of oxygen. [2]

O3+(g)O4+(g)+e-(1)– equation(1) – state symbols

ii)How does the graph provide evidence for the existence of two electron shells in oxygen? [2]

Large difference between 6th and 7th IE (1)

Which marks a different shell (closer to the nucleus) (1)

b)i)Complete the electronic configuration for an gallium atom. [1]

1s22s2 2p63s2 3p6 3d10 4s2 4p1

ii)Sketch a graph to show the five successive ionisation energies of gallium. [2]

Sharp rise between 3rd and 4th (2)

pattern the wrong way round = 1