Trends in Periodic Table (MEMORISE)

Question 1

What is Core Charge/Nuclear Charge? How do you calculate Core Charge?

Answer 1

The Core Charge is a measure of the attractive force felt by the valence shell electrons towards the nucleus.

Core Charge is calculated by the number of protons in the nucleus MINUS the number of total inner shell electrons (Number of electrons EXCLUDING THE VALENCE SHELL)

Thus,
Number of Protons - Number of Total-Inner Shell Electrons

• As the core charge increases, the valence electrons are more strongly attracted to the nucleus, meaning it is harder to lose them.

Question 2

What is the trend in core charge across the periodic table?

Answer 2

The core charge STAYS THE SAME
down the group
The core charge INCREASES across the period

Question 3

What happens to the atomic radius in the periodic table?

Answer 3

The atomic radius increases down the group

The atomic radius DECREASES ACROSS THE PERIOD

Question 4

What is the atomic radius? How do you calculate or find the atomic radius?

Answer 4

The atomic radius is a measurement used for the size of atoms.

It is the total distance from an atom’s nucleus to the outermost electron shell

The atomic radius is found by halving the distance between the nuclei of two atoms of the same element.

Question 5

What happens to the atomic radius down the group and across the period?

What is the reason behind these properties/ trends?

Answer 5

The atomic radius increases down the group

The atomic radius decreases across the period. (Left to Right)

The atomic radius increases Down the Group because the number of electron shells increases, meaning that it gets bigger and bigger, further away from the nucleus of the atom.

Also, the atomic radius decreases across the period since the electrostatic attraction increases. Across the period, the number of protons tends to increase. The greater the number of protons and negative electrons, the greater the attractive force and therefore the core charge. (Since core charge is number of protons - number of total inner electrons)

Question 6

Thus, what is the relationship between core charge and atomic radius?

Answer 6

As the core charge increases, the valence electrons are more strongly attracted to the nucleus, which means that the atomic radius decreases.

This is since the atom ‘contracts’ and pulls the **electron cloud ** closer to the nucleus, when having a higher core charge, resulting in less distance of the valence electron shell to the atoms nucleus.

Question 7

What is electronegativity? What is its relationship with core charge?

Answer 7

Electronegativity is the tendency to gain electrons.

The more strongly the valence electrons of an atom are attracted to the nucleus of the atom, the greater the electronegativity/ tendency to gain electrons.

(Think of it like a magnet. Once u throw sth like a nail, it instantly attaches itself due to the magnetic force/attraction)

This also means that weaker bonds between the valence electrons and the nucleus, mean less chance for the atom to gain electrons

Question 8

What are the trends of electronegativity in the periodic table?

Answer 8

The electronegativity DECREASES down the GROUP

and

INCREASES across the PERIOD

Question 9

What are the trends of metal reactivity and non-metal reactivity?

Answer 9

Metal reactivity:
INCREASES DOWN THE GROUP
DECREASES ACROSS THE PERIOD

Non-Metal Reactivity:
DECREASES DOWN THE GROUP
INCREASES ACROSS THE PERIOD

Question 10

What is first ionisation energy?

Answer 10

FIRST IONISATION ENERGY is the energy required to remove ONE electron from an atom of an element in its GAS PHASE.

Question 11

What is ionisation in general?

Answer 11

Ionisation is the process of removing an electron from an atom and forming an ion called ionisation.

Question 12

List the pattern/trend of Ionisation Energy

List reasons why

Answer 12

Ionisation energy decreases down the group.

This is because the number of electron shells increases down the group, meaning there is less attraction of the valence electrons towards the centre. It is held less tightly and requires less energy to move, making it easier to lose an electron rather than to gain.

Ionisation Energy INCREASES ACROSS THE PERIOD

This is because the atomic radius decreases across the period, meaning it is harder to remove an electron from an outer shell.2
(since smaller distance between valence electrons to nucleus, imply stronger bonds, making it less easier to lose electrons) Thus, MORE ENERGY IS REQUIRED TO LOSE THIS ELECTRON WILLINGLY.

Question 13

What is the relationship between atomic radius and electron shells?

Answer 13

Increased electron shells mean increased atomic radius, as the distance from the nucleus of the atom gets bigger and bigger.

Question 14

Does the size of the atom affect the core charge?

Answer 14

Yes. Atomic radius and core charge vary upon one another. A smaller atomic radius would mean a greater core charge while a bigger atomic radius would mean lower core charge..

An exception is the core charge remains the same down the group.

Question 15

What does higher and smaller atomic radius imply?

Answer 15

A bigger atomic radius implies that the distance between the valence electrons to its nucleus is larger, meaning that there is less pull and thus easier for the atom to lose electrons. (Since bigger means weaker attraction)

A smaller atomic radius implies that valence electrons are tighter and closer to the nucleus, meaning it is harder to lose electrons. Hence, they have a stronger attraction.

Question 16

What is electrostatic attraction?

Answer 16

Electrostatic attraction refers to the attraction of a negatively charged ion to a positively charged ion, and vice-versa.

Question 17

What is the definition of ‘reactivity?’ Also, what happens when metals lose electrons?

Answer 17

Reactivity refers to how easily an atom of that element loses or gains electrons.

When metals react, they lose electrons. Therefore, the reactivity of metals is a measure of how easily an atom of a metallic element can lose electrons.

Since metals lose electrons while non-metals gain.

Question 18

Relationship between ionisation energy and losing electrons?

Answer 18

A higher ionisation energy implies a greater amount of energy needed to lose an electron. Thus, greater ionisation energy means it is harder to lose the loose valence electrons

Question 19

What are the trends of water reactivity?

Answer 19

The reactivity of water increases down the group, meaning that elements tend to be more reactive lower down the periodic table

This is because the first ionisation energy tends to decrease down the group, which implies less energy is needed to remove an electron - meaning a faster rate of reaction.

Likewise, the reactivity of water decreases across the period as the first ionisation increases across the period. This means it is harder to lose an electron and react due to the greater amount of energy needed to support it. Thus, it is harder to react with water due to a significant increase in first ionisation energy.

Question 20

Relationship between first ionisation energy and reactivity?

Answer 20

The less/lower the ionisation energy, the easier it is to react with other elements

Likewise, the greater the ionisation energy, the harder it is and less likely it is to react with other elements.

Question 21

What is another reason toward why ionisation energy tends to increase across the period? (Other than the atomic radius decreasing)

Answer 21

Ionisation energy increases across the period also because of the increase in the number of protons. The increase in protons results in an increase in nuclear charge/core charge which means that the attraction between the valence shell and the nucleus of the atom becomes stronger. Because this attraction becomes stronger, there is more energy required to remove the valence electron from that atom - hence the pattern of increasing ionisation energy across the period.

Question 22

What is the relationship between atomic radius and electronegativity?

Answer 22

The smaller the atomic radius, the closer the valence shell is to the nucleus of the atom and thus results in a higher electronegativity, due to a stronger attraction and tighter bond.

Question 23

Trend of electrical conductivity?

Answer 23

Electroconductivity decreases across the period and increases down the group.