Bonds Ionic – Bond formed due to a difference in charge Loss or gain of an electron Usually forms between a metal and a nonmetal

Bonds Covalent – Bond formed from two atoms sharing an electron Commonly found in “organic” compounds (with H, C, and O, among others)

Dmitri Mendeleev Order elements by atomic mass Periodic Law – When the elements are arranged in order of increasing relative mass, certain sets of properties recur periodically used pattern to predict properties of undiscovered elements 1834 - 1907

Periodic Table Pattern H nm H2O a/b 1 H2 Li m Li2O b 7 LiH Be m/nm BeO a/b 9 BeH2 nm B2O3 a 11 ( BH3)n B nm CO2 a 12 CH4 C nm N2O5 a 14 NH3 N nm O2 16 H2O O nm OF2 19 HF F left  right across a row (period) increasing atomic mass (not relative mass); organized based on their activity and properties

Periodic Table Pattern H nm H2O a/b 1 H2 Li m Li2O b 7 LiH Be m/nm BeO a/b 9 BeH2 nm B2O3 a 11 ( BH3)n B nm CO2 a 12 CH4 C nm N2O5 a 14 NH3 N nm O2 16 H2O O nm OF2 19 HF F Na m Na2O b 23 NaH m MgO b 24 MgH2 Mg m Al2O3 a/b 27 (AlH3) Al nm/m SiO2 a 28 SiH4 Si nm P4O10 a 31 PH3 P nm SO3 a 32 H2S S nm Cl2O7 a 35.5 HCl Cl up  down column; similar properties; how the elements react with H and O some gaps were left in table for undiscovered elements; properties of these elements were predicted.

PERIODIC TABLE Non-metals Metals Metalloids

PROPERTIES OF METALS & NON-METALS Mostly solid Can be solid, liquid or gas Have shiny appearance Have dull appearance Good conductors of heat & electricity Poor conductors of heat & electricity Malleable & ductile Brittle (if solid) Lose electrons Gain or share electrons

Metals Non-metals

METALLOIDS Metalloids are elements that possess some properties of metals and some of non-metals. The most important metalloids are silicon (Si) and germanium (Ge) which are used extensively in computer chips.

Metalloids Properties of Silicon shiny conducts electricity brittle

PERIODIC TABLE Metallic character decreases going across a period. Metallic character increases going down a group F Least metallic element Cs Fr Most metallic elements

PERIODIC TABLE Seven elements exist as diatomic molecules. All others exist as monatomic (single atom).

PERIODS & GROUPS The periodic table is composed of periods (rows) and groups or families (columns). Elements in the same family have similar properties, and are commonly referred to by their traditional names.

PERIODS & GROUPS Group 2 elements are called alkaline-earth metals. These metals are less reactive than alkali metals. The group of metals in between the main group elements are called transition metals. Halogens are the most reactive nonmetals, and occur in nature only as compounds. Noble gases are un-reactive gases that are commonly used in light bulbs. Elements in groups 1-2 and 13-18 are referred to as main-group or representative groups. Alkali metals are soft metals that are very reactive. They often react explosively with other elements.

Pick a group Name of Group Elements in the group Alkali metals Properties of the elements in the group Bonds usually formed Reaction to fire Alkali metals Alkaline earth metals Transition Metals Metalloids Halogens Noble Gasses