Classification of Matter

Four classes of matter

The four classes of matter are elements, compounds, mixtures, and solutions

Homogeneous matter Appears to look similar throughout

Ex: salt, sugar, whipped cream

all parts are alike (appearance)

Question

What does the prefix “homo” mean?

Name the four classes of matter.

What are the four phases of matter?

Question

Milk in most stores is homogenized. What do you think this means?

Heterogeneous matter

Matter that has different properties

Ex: soil, cereal with raisins, concrete

Question

How is homogeneous matter different from heterogeneous matter?

Question video Why is it better to classify matter according to make-up rather than phase? Think!

What is a mixture? A combination of substances

Two or more substances that are not chemically combined

Properties of mixtures The substances in a mixture keep their separate identities (properties)

Ex: salt/pepper, sugar/water

Separating mixtures The substances in a mixture can be separated by simple physical means

Evaporation and filtration are used to separate mixtures

Types of mixtures (video) Heterogeneous mixtures are the “least mixed” of all mixtures

The different particles in mixtures are large enough to be seen

Homogeneous mixtures

Homogenous mixtures are “well mixed”

Particles are small and not easily recognized

Question

What are two ways mixtures can be separated?

Solutions (video)

A solution is a mixture in which a substance is dissolved in another, “best mixed”

Properties of a solution Particles are not large enough to be seen

Evenly spread particles Particles cannot be separated by simple physical means

Alloys (video)

Solutions of metals are alloys

Ex: gold jewelry, brass, sterling silver, stainless steel

Questions

Describe an alloy. What are two properties of a solution?

Pure substances (video) Homogeneous matter is also known as a pure substance

Properties: one kind of material with the same properties

Elements Simplest types pure substances

Made of only one type of atom

Cannot be broken down by chemical processes or heating

What is an atom? (video)

The smallest particle of an element that has the same properties of the element is the atom

Chemical symbols A short way of representing elements

Consists of one or two letters

An abbreviation for an element

Question

What are two properties of elements?

What is an atom?

Compounds (video) Pure substances made of more than one element is a compound

Ex: carbon dioxide, ammonia, sugar

Molecules Two or more atoms that are

chemically bonded Smallest part of a

compound that has the same properties of that compound

Separating compounds Compounds are made of molecules

Compounds can be broken down into simpler substances by heating and electricity

Questions

How is a molecule different from an atom?

How is a compound different from an element?

Chemical formulas

Combinations of chemical symbols are chemical formulas (C3H7OH) (NH3)

Subscript A subscript is placed to the lower right of the chemical symbol

It gives the number of atoms of the element

Questions

How is chemical symbol different from a chemical formula?

Chemical equations A description of a chemical reaction using symbols and formulas is a chemical equation

Coefficient The number used to balance a chemical equation (coefficient)

“Balanced” means the same number of reactants and products

Questions

How is a subscript different from a coefficient?

Chemical reactions

Reactants are the substances that enter a chemical reaction

Products are the substances formed by a chemical reaction

Chemical equations 2H2+O2 (reactants) 2H2O The arrow means yields

(makes) C + O2 CO2 (products)

Reactants (yield) products

Questions

What does the arrow mean in a chemical equation?

What is a chemical equation?

Questions

What is another name for a chemical reaction?

On what side of a chemical reaction would you find the reactants?

Products?