Matter and Change Chapter 1

Theoretical Chemistry Branches of Chemistry Organic Chemistry Inorganic Chemistry Physical Chemistry Analytical Chemistry Biochemistry Theoretical Chemistry ….and many more!

anything that has mass and takes up space Matter anything that has mass and takes up space pure substances – compounds and elements mixtures – two or more pure substances mixed in the same container…not bonded

Pure Substances Element – A pure substance made of only one kind of atom Atom – An atom is the smallest unit of an element that maintains the properties of that element

Pure Substances Compound – A substance that is made from the atoms of two or more elements that are chemically bonded. Molecule – the smallest unit of an element or compound that retains all of the properties of that element or compound

How can a molecule describe an element? Huh? How can a molecule describe an element?

H2, Br2,O2, F2, I2, N2, Cl2, Diatomic Elements Uncle Henry BrOFINCl These elements are found as a pair, chemically bonded to one another. They are not always in pairs in a compound but are in pairs when they are found as the pure element. Ex: H2O (only 1 oxygen)

Compounds and Elements

space filling model molecular model chemical formula structural formula

SHAPE definite shape indefinite shape VOLUME definite volume indefinite volume Solid Liquid Gas

States of Matter The particles of a solid are packed together in relatively fixed positions. The particles have strong attractive forces and low energy. (s)

States of Matter The particles of a liquid are close together but can most past one another. These particles have more energy than those of a solid, and this energy is what allows a liquid to flow. Pure liquid = (l) A liquid solution = (aq)

States of Matter The particles of a gas move rapidly past one another, and are at a great distance apart from one another compared to their size. These particles have very high energy. (g)

States of Matter - Plasma A plasma is a very high temperature physical state of matter in which atoms lose their electrons. Plasma is found in fluorescent light bulbs and plasma Televisions.

Solid, Liquid, or Gas?

What two phase changes are occurring at the same time?

Physical Properties physical property – a characteristic that can be observed or measured without changing the identity of the substance state of matter melting point mass color

Physical Changes physical change – a change in a substance that does not involve a change in the identity of the substance breaking cutting dissolving boiling tearing

All phase changes are physical changes.

Chemical Properties chemical property – a characteristic that can be observed or measured with a change in the identity of the substance flammability reacts with an acid reacts with oxygen

Chemical Changes chemical change – a change in a substance that does involve a change in the identity of the substance color change gas released (often with an odor) energy change (light, heat, …) precipitate formed …four good indications of a chemical change.

Precipitate aqueous – dissolved in water precipitate – a solid formed from two aqueous solutions during a chemical reaction

Extensive vs. Intensive Properties extensive – DOES depend on the amount of matter present Example: mass, volume, amount of energy within a substance intensive – does NOT depend on the amount of matter present Examples: color, melting point, density, luster If mass and volume are extensive properties, why is density an intensive property?

Classification of Matter

Decomposition of Water water ® hydrogen + oxygen 2H2O(l) ® 2H2(g) + O2(g) ® + reactants yield products

Hoffman Apparatus The Hoffman Apparatus is used to decompose water into its pure elements. This is a chemical change. The new substances (hydrogen gas and oxygen gas) did not retain the properties of the original substance (water).

Heterogeneous Mixtures Homogeneous Mixtures the same throughout…each sample contains the same ratio of ingredients (Also called solutions) Heterogeneous Mixtures different throughout…each sample contains a different ratio of ingredients

Separation of Mixtures density PHYSICAL changes only magnetism by hand evaporation filtration chromatography

Separation of elemental Fe magnetism This doesn’t work with iron that is bound into a compound, only with elemental Fe.

Distillation Apparatus

Mixture or Pure Substance?

Homogeneous Mixture, Heterogeneous Mixture or Pure Substance?