Periodic Table: Key Concepts on Elements, Trends, and Electron Behavior

What group of elements is known for having one valence electron?

Alkali Metals (Group 1).

What is a characteristic of alkaline earth metals?

They have two valence electrons and are less reactive than alkali metals.

What is the mnemonic to remember the groups of alkali and alkaline earth metals?

'Alkali' for Group 1 and 'Alkaline Earth' for Group 2.

What defines transition metals?

They are D-block elements with varying valence electrons and properties.

How many valence electrons do halogens have?

Seven valence electrons.

What is the defining feature of noble gases?

They have a full valence shell and are known as inert gases.

What does the Octet Rule state?

Most elements aim for a full valence shell of eight electrons.

What do cations and anions represent?

Cations are positively charged ions (lose electrons), while anions are negatively charged ions (gain electrons).

How does the atomic radius change across a period?

It decreases from left to right due to increased effective nuclear charge.

What happens to atomic radius down a group?

It increases due to the addition of new energy shells.

What is electronegativity?

An atom's ability to attract electrons from another atom.

Which element is the most electronegative?

Fluorine (4.0 Pauling units).

What is the trend of electronegativity in the periodic table?

It increases from bottom-left to top-right.

What is the smallest atom?

Helium.

What is the largest atom?

Francium (or Cesium).

What is the significance of Linus Pauling in chemistry?

He pioneered the concept of electronegativity and contributed to the understanding of DNA structure.

What is the ionization energy?

The energy required to remove an electron from an atom.

What are isoelectronic species?

Atoms or ions with the same electron configuration.

What happens to the size of isoelectronic species with more protons?

The one with more protons will have a smaller radius due to stronger nuclear pull.

What defines the effective nuclear charge?

The net positive charge experienced by an electron in a multi-electron atom.

What is electron shielding?

Inner electrons shield outer electrons from the full attractive force of the nucleus.