Physical Science Chpt. 11  Chemical Bonds  Compounds  Ionic bonds  Covalent bonds  Short Version

Compound  Chemical formulas—tell what elements compounds contain and the ratio of those atoms – Ex CaCl 2, NaCl, H 2 0  A certain number of atoms of each element must combine together— has to do with oxidation number of the atoms  Properties are different from elements contained in the compound  Formed because elements like to be stable and forming compounds help them to be more stable

Compound  Determining compound formula – Find all elements on periodic table, therefore determining their oxidation number – Criss cross oxidation numbers for elements – Don’t forget polyatomic ions that have combined oxidation numbers  Table 11-1 familiar compounds

Atoms  Atom is chemically stable if the outer energy level has 8 electrons – So it will share, lose or gain electrons to get to 8, therefore forming compounds (bonds)

Chemical Bonds  Force that hold together atoms in a substance

Ions  An atom that is either positively or negatively charged, will form ionic bonds

Ionic Bonds  Force of attraction between opposite charges of ions – One atom loses and one atom gains electrons – Normally between solids – Makes the compound neutral

Covalent Bonds  Attraction that forms between atoms when they share electrons  Share electrons  Normally between liquids and gases  Molecules – Neutral particles formed as a result of sharing electrons

Molecules  Formed in compounds  Polar Molecules – One that has a positive end and an negative end – Example—water  Non-polar Molecules – One that does not have oppositely charged ends

Oxidation Number  Is a positive or negative number assigned to an element to show its combining ability

Oxidation/Outer Electrons Group NumberOuter Energy Level Electrons Oxidation Number Vary / stable

Binary Compounds  Composed of two elements

Hydrate  Hydrate – Compound that has water chemically attached – Written CoCl 2. H 2 0  Anhydrous – Without water

Polyatomic Ions  Page 318  Need to know  A positively or negatively charged covalently bonded group of atoms

Chemical Risks at Home  Toxic  Poisonous  Corrosive  Flammable