Compounds

most of the substances you encounter are compounds that contain combined elements in fixed, definite proportions the chemical formula of a compound indicates the proportions of different atoms in the compound

• H20-2 hydrogen, one oxygen

Subscripts are a part of a compound definition

• if the Subscript Changes, the formula is no longer the same compound

  • CO = carbon monoxide-pollutant

  • CO₂ = Carbon dioxide -harmless

formulas list the most metallic elements first

Those to the left of the periodic table are metal-like than those to the right

In a column, elements toward the bottom are more metal-like

Ionic compounds - composed of one or more from cations cations paired with one or more Anions.

• cations are metals

• Anions are nonmetals

  • transfer of electrons

• positive charge from cations equal the negative charge from the anions

Molecular Compounds - 2 or more nonmetals. Can combine in different ratios

• shares electrons

leave out charges

Charge of anion becomes subscript of cations and vice versa