Chemistry: Chapter 5 - The Periodic Law

Periodic Law

• The Periodic Law states that the chemical properties of elements are periodic functions of their atomic numbers.
• This means that elements with similar properties appear at regular intervals in the periodic table.

Lanthanides

• The Lanthanides are a series of 15 metallic elements with atomic numbers 57 to 71.
• They are located at the bottom of the periodic table and are often grouped with the elements Scandium and Yttrium.
• They are characterized by their similar chemical properties and are often difficult to separate from each other.

Actinides

• Actinides are a series of 15 radioactive elements with atomic numbers 89 to 103.
• They are placed at the bottom of the periodic table and share similarities with the Lanthanides in their properties.
• All Actinides are radioactive and are typically found in trace amounts in nature.

Alkali Metals

• Alkali metals are a group of elements located in Group 1 (IA) of the periodic table.
• They are soft, highly reactive metals that readily lose their outermost electron to form cations with a +1 charge.
• Examples include Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr).

Similar Properties

• Elements with similar properties fall into the same groups (columns) of the periodic table.
• Elements within a group have the same number of valence electrons, which are the electrons in the outermost shell.

Organization of Elements

• The periodic table organizes elements in order of their atomic numbers.
• This determines the number of protons in an atom's nucleus.

Alkaline-Earth Metals

• Alkaline-Earth metals are a group of elements located in Group 2 (IIA) of the periodic table.
• They are reactive metals that readily lose their two outermost electrons to form cations with a +2 charge.

Transition Elements

• Transition Elements are located in Groups 3 to 12 (IIIB to IIB) of the periodic table.
• They are characterized by their ability to form ions with multiple charges, contributing to their diverse chemical properties.

Halogens

• Halogens are nonmetallic elements found in Group 17 (VIIA) of the periodic table.
• They are highly reactive and have a strong tendency to gain an electron to form anions with a -1 charge.

Ionization Energy

• Ionization energy is the minimum energy required to remove an electron from a gaseous atom in its ground electronic state.
• Higher ionization energy makes it harder to remove an electron.

Cation

• A cation is a positively charged ion formed when an atom loses one or more electrons.

Electronegativity

• Electronegativity is a measure of an atom’s ability to attract electrons towards itself when forming a chemical bond.

Anion

• An anion is a negatively charged ion formed when an atom gains one or more electrons.

Atomic Radius

• Atomic radius is the distance from the nucleus of an atom to its outermost electron shell.

Valence Electrons

• Valence electrons are the electrons in the outermost shell of an atom, and are responsible for chemical bonding.

Ion

• An ion is an atom or molecule that has gained or lost one or more electrons, resulting in a net positive or negative charge.