Chapter 2-2 Combinations of Atoms

How atoms combine Atoms combine in two ways; When atoms combine they lose their chemical properties and take on new ones. 1. Sharing electrons in outer energy levels Molecules – smallest part of a compound made by sharing electrons Compound – 2 or more elements chemically combined H2O – is a molecule

Water Molecule

Ions – positive or negative charged atom 2. Gaining or losing electrons in outer energy levels Losing electrons - positive charge atom Gaining electrons – negative charge atom Ions – positive or negative charged atom Ions are attracted by the unlike charges NaCl – table salt is an ionic compound

Salt Na – sodium - one electron in outer energy level - loses electron - positive ion Cl – chlorine - 7 electrons in outer energy level -gain electron - negative ion

Aluminum oxide Al2O3 Al loses 3 e = + ion O gains 2 e = - ion Takes on all new properties.

Mixture Mixture – combination of 2 or more compounds but each retains its own properties Can easily be separated Lucky Charms - example of mixture Marshmallows oat cereal

Solution Solution – one substance is dissolved into another substance Each substance retains its properties yet they appear as one substance. The distribution of the substances are the same throughout the solution. Can be separated

Parts of a solution Solute: part being dissolved Solvent: part doing the dissolving Dissolving: moving of solute between particles of solvent Bipolarity of water helps it to dissolve

Compounds Difficult to separate Must use chemical means Chemical change – converting one substance into its elements. C6H12O6

States of Matter

Solid Atoms strongly attracted Tightly packed Vibrate very slowly to and fro Definite shape and volume

Liquid Particles further away Attraction weaker Move over and around No definite shape/take shape of container Definite volume

Gases Attraction minimal Movement – fast No definite shape No definite volume Fill entire container place into

Plasma – 4th state of matter Plasma – gaseous state made of free flowing ions and electrons Lightning Fluorescent bulb Stars Sun

Changing states of matter Energy is added or removed Adding energy = solid to liquid to gas Removing energy – gas to liquid to solid Freezing pt. – l to s Boiling pt – l to g

Changing States of Matter