 In addition to physical properties, elements have chemical properties.  Chemical properties describe the way elements interact with one another.

 Elements in the same area of the periodic table have similar properties.  Alkali metals – soft and extremely reactive  Alkaline earth metals – light and soft, not as reactive as alkali  Transition metals – mostly hard and shiny, react slowly with other substances

 Metalloids – share properties of metals and nonmetals. › Semiconductors – at high temperatures they conduct electricity, at low temperatures they act as insulators  Nonmetals – poor conductors, brittle solids or gases

 Noble gases – the far right column, do not react with other elements.  Halogens – to the left of the Noble Gases, highly reactive

 Indicators – materials that change color in the presence of acids or bases  Acids – 0-7 on pH scale, taste sour, release hydrogen ions in solution  Bases – 7-14 on pH scale, taste bitter, feel slippery, release hydroxide ions in solution

 Measures the strength of acids and bases.  7 = neutral, pure water  The far ends of the scale, near 0 or 14, are the strongest acids and bases.

 Salts are formed by reactions between acids and bases.  Water and salt are created when acids and bases mix this is called neutralization.  Ionic bond – forms when one atom takes an electron from another atom  Electrolytes – allow electric current to flow when dissolved in a liquid