Question 1

Which statement best explains why atomic radius increases as you move down a group in the periodic table?

Accepted Answer

The number of occupied electron shells increases, causing the valence electrons to be further from the nucleus.

Question 2

What is the core charge of an aluminum atom ($\mathrm{Al}$) with atomic number 13 and electron configuration $1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^1$?

Accepted Answer

$+3$

Question 3

Which of the following elements has the highest first ionisation energy?

Accepted Answer

Neon ($\mathrm{Ne}$)

Question 4

Why does electronegativity decrease as you move down a group in the periodic table?

Accepted Answer

Valence electrons are further from the nucleus due to more electron shells, reducing the nucleus's pull.

Question 5

A patient is exposed to a toxic halogen gas. Based on periodic trends, which property of halogens makes them highly reactive?

Accepted Answer

Halogens have high electronegativity and are one electron short of a full valence shell.

Question 6

Which trend is observed in ionisation energy as you move from left to right across a period?

Accepted Answer

Ionisation energy increases due to increasing core charge and stronger attraction to the nucleus.

Question 7

Which group in the periodic table contains elements with 2 valence electrons and is known for forming basic oxides?

Accepted Answer

Group 2: Alkaline earth metals

Question 8

If sodium ($\mathrm{Na}$) has 11 protons and 10 core electrons, what is its core charge?

Accepted Answer

$+1$

Question 9

Which explanation best describes why atomic radius decreases across a period?

Accepted Answer

Core charge increases, pulling valence electrons closer to the nucleus.

Question 10

A scientist compares the reactivity of potassium ($\mathrm{K}$) and sodium ($\mathrm{Na}$). Which periodic trend explains why potassium is more reactive?

Accepted Answer

Potassium has a larger atomic radius and lower ionisation energy, making it easier to lose its valence electron.

Question 11

Which of the following best describes the relationship between core charge and the attraction of valence electrons?

Accepted Answer

Higher core charge results in stronger attraction of valence electrons to the nucleus.

Question 12

Which element would you expect to have the lowest electronegativity?

Accepted Answer

Cesium ($\mathrm{Cs}$)

Question 13

Why do noble gases (Group 18) have very low chemical reactivity?

Accepted Answer

They have a full valence shell, making them stable and unlikely to gain or lose electrons.

Question 14

Which of the following statements about transition metals is correct?

Accepted Answer

Transition metals are found in groups 3-12 and often form colored compounds.

Question 15

A chemist is designing a new battery using elements from Group 1. Which property of these elements is most important for battery function?

Accepted Answer

Low ionisation energy, allowing easy loss of valence electrons.

Question 16

Which trend in the periodic table explains why fluorine ($\mathrm{F}$) is the most electronegative element?

Accepted Answer

Electronegativity increases across a period and up a group, reaching a maximum at fluorine.

Question 17

Which of the following best describes the trend in atomic radius as you move from top to bottom within a group?

Accepted Answer

Atomic radius increases due to the addition of electron shells.

Question 18

Which element would require the most energy to remove its first electron?

Accepted Answer

Helium ($\mathrm{He}$)

Question 19

A researcher observes that the atomic radius of chlorine ($\mathrm{Cl}$) is smaller than that of sodium ($\mathrm{Na}$). Which explanation is most accurate?

Accepted Answer

Chlorine has a higher core charge, pulling its valence electrons closer to the nucleus.

Trends in the Periodic Table: Structure, Properties, and Periodic Trends

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