The study of matter and the changes that it undergoes.

Matter Anything that has mass and takes up space Substances Definite composition Mixtures 2 or more pure substances physically combined (each substance retains its own properties) Variable Composition

Substances Compound 2 or more different elements chemically combined Can be broken down chemically into its component elements 2 or more symbols Examples: NaCl Cu 3 (PO 4 ) 2 Element Can not be decomposed or broken down ONLY 1 Symbol Examples: O Ni

Element Atoms Nucleus Proton Neutron Electron Energy levels center outside

Compound Ionic: Metal and a nonmetal Covalent (Molecular): 2 or more nonmetals

Matter SubstanceMixture Homogeneous 1 phase of matter Uniformly mixed Solutions Will not separate Heterogeneous 2 or more different phases Not uniform Will eventually separate

Homogenous Aqueous: Water solution Example: Salt water Tincture: Alcohol Solution Examples: Iodine Amalgam: Mercury Solution Example: Used to be used for dental fillings Alloy: Metal Solution Examples: Steel

Heterogeneous Colloid: Translucent mixture Examples: Milk Muddy water Suspension: Opaque Mixture Examples: Salad dressing

 Diatomic elements:  exist at standard conditions as two of the SAME element bonded together  hydrogen (H 2 ), nitrogen (N 2 ) and oxygen (O 2 ), plus the halogens fluorine (F 2 ) and chlorine (Cl 2 ); the halogens bromine (Br 2 ) and iodine (I 2 ) hydrogennitrogenoxygen halogensfluorinechlorine bromineiodine  Monoatomic elements:  All the other elements  Exist as one atom

 Used to represent atoms, compounds, mixtures etc. in different phases.

 (aq) means aqueous and denotes that the compound or element attached to it has been mixed with water  Denotes a mixture  Example:  NaCl (aq)  The NaCl is dissolved in water

Solid  Denoted by (s) next to a compound or element  Fixed volume and shape  Molecules/atoms are close together or touching

 Liquid  Denoted by (l) next to a compound or element  Fixed volume, shape can change  Takes the shape of the container  Molecules/atoms are not touching and further apart

 Gas  Denoted by (g) next to a compound or element  Neither a fixed volume or shape  Takes the shape and volume of the container  Molecules/atoms are far apart

 2 or more substances physically mixed together  Mixtures can be physically separated (physically separated: there will be no change in composition of the substances)

 Separate a solid from a liquid

 Separate a dissolved substance from a liquid

 Separate a mixture based on attraction for the solvent

 Separate 2 or more liquids based on their differences in boiling points

 Characteristics that can be observed without changing the composition of the material Examples:  Color  Density  Melting and Boiling points

 Characteristics that can only be observed by changing the composition Examples:  Flammability  Combustible  Reactivity with air, water, etc

 A change that occurs WITHOUT a change in composition Example:  Bending  Cutting  Melting  Boiling

 A change in matter that occurs with a change in compostion  Also known as a chemical reaction Examples:  Burning (combustion)  Reacting with acid, base, water, etc…

How do you know if a chemical change has occurred?  An gas is produced (see bubbling or smell the odor)  Color changes  Precipitate is formed  Heat is released or absorbed

Energy Ability to do work Kinetic Energy Energy of motion Potential Energy Stored energy Temperature Measure of the Average Kinetic Energy of the particles of a sample vs. Heat Kinetic energy of the particles (always flows from hot to cold)

In a chemical or physical change there may be a transfer of energy (heat) Exothermic process: there is a release of energy (heat) Endothermic process: there is absorption of energy (heat)

 Exothermic Reactions will feel “hot”  Endothermic Reactions will feel “cold”

Endothermic Exothermic H 2 O(l)  H 2 O(g) endo

 There are three phases of matter:  Solid  Denoted by (s) next to a compound or element  Fixed volume and shape  Liquid  Denoted by (l) next to a compound or element  Fixed volume, shape can change  Takes the shape of the container  Gas  Denoted by (g) next to a compound or element  Neither a fixed volume or shape  Takes the shape and volume of the container

 (aq) means aqueous and denotes that the compound or element attached to it has been mixed with water  Denotes a mixture  Example:  NaCl (aq)  The NaCl is dissolved in water

Matter SubstanceMixture Homogeneous Heterogeneous Element Compound