MATTER

Chemistry is the study of the composition and behavior of matter. Introduction Chemistry is the study of the composition and behavior of matter.

Matter is anything with mass and volume book air smoke

LAW OF CONSERVATION OF MATTER Matter cannot be created or destroyed, it can only be changed from one form to another.

Mass is a measure of the amount of material within an object. ***Mass is independent of gravity; weight is not!

LAW OF CONSERVATION OF MASS Mass cannot be created or destroyed, it can only be changed from one form to another.

10 g reactants → 10 grams products 20 mlc reactants → 20 mlc products ***The Law of Conservation of Mass tells us that what we start with must EQUAL what we end up with!

Volume is the amount of space occupied by an object

Physical States of Matter Solid definite shape and definite volume

Liquid definite volume, takes shape of container (indefinite shape)

Gas takes volume and shape of container

Plasma Gas particles that have broken apart to become positive ions & stream of electrons

Physical vs Chemical Changes 1. In physical changes, the identity of a substance remains the same. Example: liquid water is heated to form water vapor H2O (l) → H2O (g)

2. In chemical changes, the identities of substances change and new substances form. Example: Mercury (II) oxide → mercury + oxygen 2HgO → 2Hg + O2

Evidence of Chemical Change Formation of a gas (bubbles) Evolution of heat and/or light Formation of a precipitate

Solution A + Solution B → solid + solution C Precipitate: A solid produced in a chemical reaction between solutions Solid “falls out” of solution Solution A + Solution B → solid + solution C [two homogeneous mixtures] [heterogeneous mixture]

A change in color is not a reliable indicator of a chemical change.

In chemical equations, the reactants are on the left side of the arrow, and the products are on the right side of the arrow. Reactants → Products

Examples: 2Na + Cl2 → 2NaCl Reactants → Products 2H2 + O2 → 2H2O

Properties of Matter Chemical properties can only be identified by trying to cause a chemical change. Examples include reactivity with oxygen (rusting of iron), flammability

Physical properties can be determined without changing the nature of the substance. Examples include color, state, texture, melting point, boiling point, density

Two types of physical properties: Intensive Physical Properties- depend only on the identity of the substance Examples: density, boiling point, melting point

2. Extensive Physical Properties depend on the amount of substance present Examples: volume, mass, length, width

Classification of Matter All matter is classified as a PURE SUBSTANCE or a MIXTURE.

1. Pure substances include elements and compounds.

A. Elements: All matter is composed of elements Fundamental unit of matter Composed of one kind of atom Cannot be broken down by ordinary chemical means

-Currently more than 114 identified Each has specific properties and characteristics Each has a unique symbol

First is capitalized, second is not Chemical Symbols: One or two letters First is capitalized, second is not often first letter or first two letters of the name Carbon C Calcium Ca Boron B Bromine Br

Some symbols are derived from their Latin names: Iron Fe (Ferrum) Sodium Na (Natrium) Silver Ag (Argentum)

B. Compounds The chemical combination of two or more elements Has a formula Can be broken down by ordinary means into elements

H2O is a compound made up of the elements hydrogen and oxygen NaCl is a compound made up of the elements sodium and chlorine

Examples of Pure Substances: pure water (compound): H2O not tap water carbon (element):C sodium chloride (compound):NaCl

Sodium chloride (table salt) Each pure substance has unique properties allowing us to recognize and distinguish one from another. Sodium Chlorine Sodium chloride (table salt) soft, silvery metal reacts violently with water pale greenish yellow gas poisonous colorless crystals relatively non-toxic dissolves easily in water

2. Mixtures: Each part of a mixture retains its original properties Most matter = mixtures

All mixtures can be separated into their original parts by using physical changes/properties.

Two types of mixtures: 1. Homogeneous- Composition uniform throughout Homogeneous mixtures are also called SOLUTIONS All pure substances are homogeneous.

EXAMPLES: salt water sugar water air

2. Heterogeneous Composition varies in properties and appearance throughout Most mixtures are heterogeneous

EXAMPLES: sand in water salt and sugar tap water concrete

MATTER Pure Substances Mixtures Homogeneous Mixtures Heterogeneous Mixtures Compounds Elements

Energy is the ability to do work ENERGY OF MATTER Energy is the ability to do work

Every change in matter involves a change in energy. Endothermic processes absorb energy Exothermic processes release energy

Law of Conservation of Energy: Energy cannot be created or destroyed, it can only be changed from one form to another.

Heat is the energy transferred between objects that are at different temperatures. Temperature is a measure of the average kinetic energy of the particles in an object

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