Chapter 5: The Periodic Table and Periodic Law

Periodic Law

States that when the elements are arranged by increasing atomic number, there is a periodic repetition of their properties.

Groups

A vertical column of elements in the periodic table arranged in order of increasing atomic number; also called a family.

Periods

A horizontal row of elements in the modern periodic table.

Representative Elements

Elements from groups 1, 2, and 13-18 in the modern periodic table, possessing a wide range of chemical and physical properties.

Transition Elements

Elements in groups 3-12 of the modern periodic table and are further divided into transition metals and inner transition metals.

Metals

An element that is solid at room temperature, a good conductor of heat and electricity, and generally is shiny; most metals are ductile and malleable.

Alkali Metals

Group 1 elements, except for hydrogen, they are reactive and usually exist as compounds with other elements.

Alkaline-Earth Metals

Group 2 elements in the modern periodic table and are highly reactive.

Lanthanide Series

In the periodic table, the f-block elements from period 6 that follow the element lanthanum.

Actinide Series

In the periodic table, the f-block elements from period 7.

Nonmetals

Elements that are generally gases or dull, brittle solids that are poor conductors of heat and electricity.

Halogens

Highly reactive group 17 elements.

Noble Gases

Extremely unreactive group 18 elements.

Metalloids

An element that has physical and chemical properties of both metals and nonmetals.

Atomic Radius

The measure of the size of an atom, typically defined as half the distance between the nuclei of two identical atoms that are bonded together.

Ion

An atom or bonded group of atoms with a positive or negative charge.

Ionization Energy

The energy required to remove an electron from a gaseous atom; generally increases in moving from left-to-right across a period and decreases in moving down a group.

Octet Rule

States that atoms lose, gain, or share electrons in order to acquire the stable electron configuration of a noble gas.

Electronegativity

Indicates the relative ability of an element’s atoms to attract electrons in a chemical bond.