The Periodic Table

The Periodic Table is a chart that organizes all the elements in a way that shows patterns – both similarities and differences among the elements. Elements are listed by increasing atomic number.

The horizontal rows are called periods. There are 7 periods. The vertical columns are called groups. There are 18 groups. Elements in the same group have similar chemical properties.

Periods Each period corresponds to the energy levels found outside an atoms nucleus The period that an element is located in tells you what the highest energy level is that will contain electrons

Periods The most energy levels found in an atom (currently) is seven which corresponds to the seven periods in the table Example Potassium (K) is located in period 4 and thus will have its valence electrons in the fourth energy level

Period 1 Period 2 Period 3 Group 1 Group 2 3 4 5 18 Period 7

Special Groups Group 1 elements are known as the alkali metals. Group 2 elements are known as the alkaline earth metals. Group 17 elements are called halogens. Group 18 elements are called noble gases. Groups 3-12 are called transition metals. The Lanthanides and Actinides are the excerpts at the bottom.

Group 1 – Alkali Metals Have only one e- in the valence shell Most reactive of all metals – reactivity increases as you go down the group Hydrogen is an exception! Has one valence electron but is classified as a non-metal

Group 2 – Alkaline Earth Metals Has two e- in valence shell Become increasingly soluble with increase in temperature

Group 18 – Noble Gases Generally are chemically inert meaning they do not react with other elements This is because they already have 8e- in their valence shell causing them to be stable (He only has 2 valence e-) Only He and Ne are truly inert – others will react in limited amounts under specific conditions

Group 17 – Halogens Halogen means “salt former” – form salts when reacting with a metal Most exist as diatomic molecules in gaseous state Ex. Cl2 All are one e- short of a full valence shell causing them to be very reactive Are non-metals

Transition and Rare Earth Metals Some of the rest of the elements in the periodic table fall under these two categories Transition metals are groups 3 – 12 Rare earth (inner transition) metals are broken down further into actinides and lanthanides

Transition and Rare Earth Metals These are also called the inner transition elements and they belong here

Representative Elements Groups 1, 2 (s block) and 13-18 (p block) are often called representative elements. They are sometimes labelled 1A, 2A, 3A, …8A

These elements are called the representative elements

The Periodic Table

There are 3 major sections of elements in the periodic table: Metals Non-metals Metalloids Metals are located to the left of the “staircase line” and non-metals are to the right (except H). Metalloids border the line.

Properties of Metals Luster (shiny) Good conductors High density Physical Properties Chemical Properties: Luster (shiny) Good conductors High density High melting point Malleable/bendable Solid at room temperature (except Hg) Easily lose electrons Corrode easily (ex: rusting or tarnishing) Low electronegativity

Properties of Non-metals Physical Properties: Dull Poor conductor Brittle Not malleable Low density and melting point Chemical Property: Tend to gain electrons High electronegativity

Properties of Metalloids Metalloids border the “staircase” and tend to have some properties of both metals and non-metals. solids can lose or gain electrons semi-conductors of electricity (Conduct heat and electricity better than non metal but not as well as metals Shiny or dull Malleable

The Periodic Table