12.3 The Periodic Table

The Periodic Table - The periodic table organizes the elements according to how they combine with other elements (chemical properties). - The periodic table is organized in order of increasing atomic number.

The Periodic Table group: columns period: rows

Groups of the Periodic Table Alkali metals INCLUDES: hydrogen lithium sodium potassium - highly reactive - soft and silvery in pure form

Groups of the Periodic Table Alkaline earth metals INCLUDES: beryllium magnesium calcium - bond easily with oxygen:

Groups of the Periodic Table Halogens INCLUDES: fluorine chlorine bromine iodine - tend to be toxic gases or liquids - form salts with alkali metals:

Groups of the Periodic Table Noble gases INCLUDES: helium neon argon - do not naturally form chemical bonds with other atoms because of full electron energy levels - almost always found in their pure state

Transition Metals - usually good conductors of heat and electricity

Phases of the Elements Phases at room temperature: - most are solids - 2 are liquids (blue above) - 11 are gases (green above)

Metals, Nonmetals, Metalloids Metalloids: have properties of both metals and nonmetals Nonmetals: good insulators, brittle Metals: good thermal and electrical conductors, malleable, ductile

Periodic Properties of Elements Periodicity means properties repeat each period (row) of the periodic table.

Atomic Mass - The mass of individual atoms is extremely small - To make calculations easier, scientists use the atomic mass unit (amu). - One atomic mass unit is about the mass of a single proton or neutron (1.66 x 10-24 grams) The atomic mass of any element is the average mass (in amu) of an atom of each element.