Periodic Trends and Properties: Electronegativity, Atomic Size, and Ionization Energy

Group

A vertical column on the periodic table.

Mendeleev

The scientist who first arranged the periodic table.

Periodic Table Arrangement

The elements are arranged in order of increasing atomic number.

Periodic Law

States that when the elements of the periodic table are arranged in order, there are periodic patterns in their physical and chemical properties.

Alkali Metals

Group 1 elements.

f Block

The 2 rows on the bottom of the periodic table.

Transition Metals

The d block elements.

Ion

An atom with a positive or negative charge, formed when it loses or gains electrons.

Atomic Size

Mainly due to the number of occupied energy levels.

Atomic Size Trend Across a Period

Decreases from left to right due to increased number of protons.

Atomic Size Trend Down a Group

Increases due to a greater number of energy levels.

First Ionization Energy

The amount of energy required to remove the most loosely held electron from an atom.

Second Ionization Energy

The amount of energy required to remove a second electron, which is always more than the first.

Potassium Ionization Energy

A large increase in ionization energy occurs when the second electron is removed, as it attains a noble gas configuration.

Ionization Energy Trend

Increases across a period and decreases down a group.

Positive Ion Size

Always smaller than the size of the neutral atom from which it was made.

Negative Ion Size

Always larger than the size of the neutral atom from which it was made.

Fluorine Electronegativity

Has the highest electronegativity with a value of 4.0.

Electronegativity

The ability of an atom to attract electrons to itself in a chemical bond or reaction.

Electronegativity Trend Down a Group

Decreases as you move down a group.

Group 18 Electronegativity

Elements do not have defined values for electronegativity.

Electronegativity Trend Across a Period

Increases as you move across a period.