Periodic table

Arrangement Mendeleev arranged the first periodic table. Arranged by increasing atomic mass. Periodic Law: arranged in order of increasing atomic number. Repetition of properties.

Arrangement Periods/Series: horizontal rows

Arrangement Groups/Families: vertical columns

Metals Physical Properties Good electrical conductors Solids at room temperature Good heat conductors High melting point High density Lustrous High boiling point Ductile Malleable

Metals Chemical Properties Lose valence e- easily Low Electronegativity Corrode easily

Alkali Metals React with water Not found in nature Soft 1 valence electron Oxidation of +1 Loses 1 electron to form bonds Lower melting and boiling points

Alkaline Earth Metals React with Halogens to form salts Not found in nature Low density Found in molecules in earth’s crust 2 valence electrons Oxidation of +2 Loses 2 electrons to form bonds

Transition Metals Vary in oxidation states Different number of valence electrons Mercury

Inner Transition Metals Lanthanides Actinides “Pull out” rows in periods 6 and 7 Trans-uranium: man-made (nuclear chemistry)

Nonmetals Physical Properties Mostly gas at room temperature. Poor conductors of heat Poor electrical conductors Brittle Non-lustrous Low melting and boiling points

Non-metals Chemical Properties Gain or share valence electrons

Halogens (Nonmetals) Form salts when bonded to alkaline earth metals Form acids when bonded to Hydrogen 7 valence electrons Oxidation of -1 Readily reactive

Noble Gases (Nonmetals) Unreactive/inert Odorless Colorless 8 valence electrons (2 for He) Full octet (outer shell)

Metalloids Similar to both metals and nonmetals. Different conditions change properties. Form alloys with metals. “Stair-step” elements

Valence and trends

Valence Electrons Valence electrons – Electrons in an atom’s highest-numbered energy level. How many are in each of the examples?

Valence Electrons Shortcut You can tell how many valence electrons any atom should have by its position in the periodic table. 1 2 3 4 5 6 7 8 variable

Octet Rule 8 electrons in outer shell is most stable (one exception) Atoms will combine to make the octet full, giving them the same electron configuration as the closest noble gas. How many electrons do each element (from the example) want to lose or gain?

Atomic Radii (AR) Center of the nucleus to edge of the electron cloud.

Atomic Radii (AR) Increases down a group Each new energy level adds radius Electrons have more room to move around

Atomic Radii (AR) Decreases across a period More protons and electrons in the same energy level (same amount of space) Increased attraction pulls the e- cloud closer to the nucleus (like magnets)

Electronegativity (EN) Ability to gain or hold electrons Forms a negative ion (anion) A + e- A- + E Does not include Noble Gases

Electronegativity (EN) Decreases down a group As you move down, space is added between e- and nucleus Lessens attractive force between p+ and e- Easier for e- to be removed from atom

Electronegativity (EN) Increases across a period More e- in the same energy level, e- are held more tightly by larger attractive force of nucleus

Ionization Energy (IE) Energy put into molecule to remove outer shell electrons (valence electrons) Forms a positive ion (cation) A + E A+ + e-

Ionization Energy (IE) Decreases down a group More space between nucleus and electrons Less energy to remove e- due to less attractive force

Ionization Energy (IE) Increases across a period More e- in the same energy level Held tighter because of higher attractive force from nucleus More energy to remove e-