Question 1

What is periodicity in the context of the periodic table?

Accepted Answer

Periodicity refers to the recurring trends that are observed in the properties of elements as you move across or down the periodic table. These trends arise due to the regular variations in atomic structure, such as electron configurations, which influence properties like atomic radius, ionization energy, and electronegativity. Understanding periodicity is crucial for predicting the behavior of elements in chemical reactions, a key aspect of the IB DP Chemistry curriculum.

Question 2

How does atomic radius change across a period and down a group?

Accepted Answer

As you move across a period from left to right, the atomic radius generally decreases. This is because the increase in nuclear charge pulls the electrons closer to the nucleus, despite the addition of more electrons. Conversely, as you move down a group, the atomic radius increases due to the addition of electron shells, which outweighs the increase in nuclear charge. These trends are fundamental to understanding periodicity in Chemistry.

Question 3

Why does ionization energy generally increase across a period?

Accepted Answer

Ionization energy, the energy required to remove an electron from an atom, generally increases across a period. This is because the effective nuclear charge increases, making it more difficult to remove an electron as the attraction between the nucleus and the electrons becomes stronger. This trend is a key concept in periodicity and is important for predicting the reactivity of elements, a topic covered in the IB DP Chemistry syllabus.

Question 4

What is the trend in electronegativity across periods and down groups?

Accepted Answer

Electronegativity, the ability of an atom to attract electrons in a chemical bond, tends to increase across a period due to the increasing nuclear charge, which attracts electrons more strongly. However, electronegativity decreases down a group because the additional electron shells reduce the nucleus's pull on the bonding electrons. These trends are essential for understanding chemical bonding and periodicity in the IB DP Chemistry curriculum.

Question 5

How do the properties of metals and non-metals differ across the periodic table?

Accepted Answer

Metals, found on the left side of the periodic table, generally have lower ionization energies and electronegativities, making them good conductors of electricity and heat. Non-metals, located on the right side, have higher ionization energies and electronegativities, and they tend to be poor conductors. The transition from metallic to non-metallic character across a period is a classic example of periodicity, which is a fundamental concept in IB DP Chemistry.

Periodicity

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