Periodic Table and Properties Overview

Periodic Table, Periodic Properties and Variations of Properties

• Periodic properties and their variations in groups and periods are studied.
• Definitions for atomic size, ionisation potential, metallic character and electron affinity are included.
• Periodicity is based on atomic number for light elements.
• Modern periodic table up to period 3 is covered.
• Properties are described in terms of shells, not orbitals, with specific reference to alkali metals and halogens.

1.1 Introduction

• Elements are pure substances composed of a single type of atom.
• Elements are basic units of all matter.
• Classification of elements is crucial for organised study.
• Contributions of Dobereiner, Newland, and Mendeleev to element classification are discussed.

1.2 Salient Features of the Modern Periodic Table

• The modern periodic table has 18 vertical columns called groups.
• Elements in the periodic table are arranged from left to right in the order of increasing atomic number.

1.3 Periodic Properties

• Properties that recur at regular intervals in periods and groups are periodic properties.
• Periodic properties are influenced by the number of electrons in the outermost shell.
• Periodic properties include atomic size, metallic character, electronegativity, ionisation potential, etc.

1.4 Shells (Orbits) and Valency

• Electrons revolve around the nucleus in specific circular orbits also known as shells.
• The number of shells in an atom determines its period.
• The outermost shell determines the valence electrons, which determines an element's valency.

Group Information

• Group 1: Alkali metals
• Group 2: Alkaline earth metals
• Groups 3-12: Transition metals
• Group 13: Boron family
• Group 14: Carbon family
• Group 15: Nitrogen family
• Group 16: Chalcogens or Oxygen family
• Group 17: Halogens
• Group 18: Noble gases or Inert gases

Trends in Properties

• Atomic size generally increases down a group and decreases across a period.
• Metallic character generally increases down a group and decreases across a period.
• Ionisation energy generally increases across a period and decreases down a group.
• Electronegativity generally increases across a period and decreases down a group.
• Reactivity of metals generally increases down a group and decreases across a period.
• Reactivity of non-metals generally decreases down a group and increases across a period.

1.5.1 Atomic Size (Atomic Radius)

• Atomic radius is the distance between the centre of the nucleus and the outermost shell of an atom.
• Atomic radius increases down a group due to increasing numbers of shells.
• Atomic radius decreases across a period, due to increasing nuclear charge.

1.5.2 Nuclear Charge

• Nuclear charge is the positive charge of an atom's nucleus.
• Nuclear charge increases across a period due to an increase in the number of protons.
• Nuclear charge affecting the attraction between the nucleus and valence electrons.

1.5.3 Metallic Character

• Metals have an affinity to lose electrons easily.
• Metallic character increases down a group and decreases across a period

1.5.4 Ionisation Potential

• Ionisation energy is the energy required to remove an electron from an atom.
• Ionisation energy is higher for non-metals than metals.
• Ionisation energy is generally higher for elements higher in atomic number or with more protons within the same period.
• Ionisation energy decreases further down a group.

1.5.5 Electron Affinity

• Electron affinity is the energy released when an electron is added to a neutral atom.
• Electron affinity is generally higher for non-metals than metals.
• Electron affinity increases across a period.
• Electron affinity decreases down a group.

1.5.6 Electronegativity

• Electronegativity is the measure of an atom's ability to attract shared electrons in a chemical bond.
• Electronegativity increases across a period.
• Electronegativity generally decreases down a group.

Modern Periodic Table

• Elements in the modern periodic table are arranged in rows (periods) and columns (groups).
• Periods are horizontal rows and groups are vertical columns.
• Elements within the same group share similar properties due to the same number of valence electrons.

Mass Number

• The mass number is the total number of protons and neutrons within an atom's nucleus.
• Understanding the atomic and mass numbers is essential to distinguish between different isotopes.

This quiz covers the periodic table, focusing on periodic properties and their variations across groups and periods. Key concepts such as atomic size, ionisation potential, and electron affinity are discussed, along with historical contributions to element classification. Additionally, it covers the features of the modern periodic table through period 3.