Chapter 4: Classifying Elements

Element Symbols All symbols have one, two, or three letters. The first letter is always capitalized. The second and third letters are lowercase. Even though it is an abbreviation, there is no period at the end.

Element Symbols Some elements symbols are just the first letter of their name. Some symbols are the first two letters of their name. Some symbols are the first letter and another letter of their name. Some symbols are based on their Latin names.

Periodic Table Mendeleev was the first to arrange the elements; he arranged them by mass. Elements are on the modern periodic table are arranged by atomic number (number of protons).

Periodic Table cont. Each square of the periodic table includes the atomic number symbol element name mass number

Periodic Table cont. Isotopes are forms of the same element; they have the same atomic number (same number of protons), but they have different number of neutrons; so they have different mass numbers.

Periodic Table cont. Columns in the periodic table are called groups or families. Rows in the periodic table are called periods. There are 18 groups/families and 7 periods on the period table.

Metals Metals have these properties: solid at room temperature can be polished to shine malleable (bend w/o breaking good conductors of electricity and heat

Nonmetals Nonmetals are elements that do not have the properties of a metal. They are: solid or gas at room temp. not malleable (break when bent) not shiny

Metalloid These elements are along the zigzag line on the periodic table. They have some properties of both metals and nonmetals.

Nobel Gases They are group 18. They are inert; they don’t react or combine with other elements usually.

Energy Levels, Orbitals, & Electrons Number of Orbitals Max. Number of Electrons 1 2 4 8 3 9 18 16 32

Bohr Models Bohr models shows the number of electrons in an element.

Electron Dot Diagrams Valence electrons are the electrons in the outer energy level. Electron dot diagrams show just the valence electrons.

Electron Dot Diagrams