The Periodic Table

Question 1

The _____ is a very large molecule made by linking a series of repeating units.

Answer 1

Polymer

Question 2

What term refers to the gain of electron(s) by a species?

Answer 2

Reduction

Question 3

What is the pH formula?

Answer 3

pH = -log[H+]

Question 4

The concentration of hydrogen ions (H+) in a solution of nitric acid (HNO3) is 1.40 x 10-3 mol dm-3 .What is the pH of the solution?

Answer 4

2.85

Question 5

Which unit correctly describes concentration?

Answer 5

Amount of solute (moles)/volume of solution (litres)

Question 6

Which of these ions can be detected using Nessler’s reagent?

Answer 6

Ammonium ions

Question 7

State the trends down the periodic table

Answer 7

The number of valence shell increases and there is less attraction of valence electrons by nucleus.

Question 8

Force of attraction trends

Answer 8

Increases going up periodic table because there is one fewer energy level of electrons

Increases going right across periodic table because the nucleus gains protons and the atom has the same number of energy levels as you move across a period

Question 9

Shielding Effect trends

Answer 9

Increases going down periodic table because there is an extra energy level of electrons that will shield the outer electrons from the nucleus

Increases slightly going left on periodic table because the nucleus loses protons and the atom has the same number of energy levels as you move across a period

Question 10

Atomic radius trends

Answer 10

Increases going down because there are more energy levels of electrons and therefore more shielding.

Increases going left because as you move across a period right-to-left, an atom loses a positively charged proton and therefore its electrons become slightly less tight and compact

Question 11

Ionic radius trend

Answer 11

Increases for anions (-) because they gain an electron, which leads to more shielding

Decreases for cations (+) because they lose an electron, which means less shielding

Question 12

First ionsiation energy trend

Answer 12

Increases going right because there are more protons in the nucleus pulling in electrons, so it requires more energy to remove an outer electron

Increases going up because there are fewer energy levels and less shielding, so the outer electrons are more tightly held by the nucleus

Question 13

Electronegativity trend

Answer 13

Increases going right because there are more protons in the nucleus attracting outer electrons

Increases going up because there are fewer energy levels of electrons shielding/repelling new outer electrons

***Fluorine has greatest electronegativity because noble gases are not included due to the fact that they have a full shell of valence electrons and cannot attract more

Question 14

Electron affinity trend

Answer 14

Electron affinity increases upward for the groups and from left to right across periods of a periodic table because the electrons added to energy levels become closer to the nucleus, thus a stronger attraction between the nucleus and its electrons

Question 15

What is Le Chatelier’s principle?

Answer 15

When a system in equilibrium is subjected to a change in pressure the system will respond in a way to
minimise the effect of that change.

Question 16

Define a valence electron

Answer 16

Electrons in the outermost shell of an atom

Question 17

What factors affect ionisation energy?

Answer 17

1 The charge on the nucleus
The more protons there are in the nucleus, the more positively charged the nucleus is, and the more strongly electrons are attracted to it.

2. The distance of the electron from the nucleus
   Attraction falls off very rapidly with distance. .

Question 18

What factors affect electron affinity?

Answer 18

1. The charge on the nucleus
   more protons = more positively charged nucleus
2. The distance of the electron from the nucleus
   Attraction falls off very rapidly with distance.

The over-riding factor is the greater the distance, the less the attraction and so the less energy is released as electron affinity.

Question 19

What is the octet rule?

Answer 19

The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell.