Properties of Matter

2.1 Classifying Matter

Section 2.1: Classifying Matter

Scientists like to classify things. One way that scientists classify matter is by

its composition. Ultimately, all matter can be classified as

mixtures, elements and compounds.

Section 2.1: Classifying Matter

Pure Substances What is Matter? Anything that has mass and

takes up space (volume) Based on matter’s composition, it can be

divided into Pure Substances and Mixtures.

Matter Flowchart

MATTER

Can it be separated by physical means?

Homogeneous Mixture

(solution)

Heterogeneous Mixture Compound Element

MIXTURE PURE SUBSTANCE

yes no

Can it be decomposed by chemical means?

noyesIs the composition uniform?

noyes

Section 2.1: Classifying Matter

Pure Substances Def.-matter that always has exactly the same

composition (ex. Table salt, table sugar) Key Concept: Every sample of a given substance

has the same properties because a substance has a fixed, uniform composition.

2 Categories of substances: elements and compounds

Section 2.1: Classifying Matter

Elements Def.-a substance that cannot be broken

down into simpler substances Key Concept: An element has a fixed

composition because it contains only one type of atom.

Section 2.1: Classifying Matter

Elements: Examples of Elements Carbon (C), Aluminum (Al)- solid at RT Oxygen (O), Nitrogen (N)- gases at RT Bromine (Br), Mercury (Hg)- liquid at RT

Section 2.1: Classifying Matter Elements: Symbols for Elements

Developed in 1813 by Swedish chemist Jons Berzelius

Symbols contain 1 or 2 letters Symbols based on Latin names of the

elements Gold is Au Aluminum is Al

Section 2.1: Classifying Matter

Compounds Def.-a substance that is made from two or

more simpler substances and can be broken down into those simpler substances (elements or other compounds)

H2O→2H + O

Section 2.1: Classifying Matter

Compounds Properties of a compound differ from the

properties of the substances from which it is made.

Ex. H and O are gases at room temp.; H2O is liquid at room temp.

Section 2.1: Classifying Matter

Compounds Key Concept: A compound always

contains two or more elements joined in a fixed proportion.

Ex. SiO2- 2 (O) atoms for every 1 (Si) atom

Ex. H2O-2 (H) atoms for every 1 (O) atom

Section 2.1: Classifying Matter

Mixtures 2 types: heterogeneous and homogeneous Retain some of the properties of their

individual substances Properties of a mixture are less constant

(vary) than the properties of a substance.

Section 2.1: Classifying Matter

Mixtures Key Concept: The properties of a mixture

can vary because the composition of a mixture is not fixed.

**Mixtures can be classified by how well the parts of the mixture are distributed throughout the mixture.

Section 2.1 Classifying Matter Mixtures: Heterogeneous and

Homogeneous Mixtures Heterogeneous- the parts of the mixture are

noticeably different from one another Ex. Sand Homogeneous-the substances are so evenly

distributed that it is difficult to distinguish one substance in the mixture from another

Ex. Water, steel

Section 2.1 Classifying Matter

Is the mixture uniform throughout? If the answer is NO, the matter is a

heterogeneous mixture. Considered the “least mixed.” Does not appear to be the same throughout. Particles are large enough to be seen and to be

separated from the mixture.

Section 2.1 Classifying Matter

Is the mixture uniform throughout? If the answer is YES, the matter is a

Homogenous mixture.

Matter Flowchart

MATTER

Can it be separated by physical means?

Homogeneous Mixture

(solution)

Heterogeneous Mixture Compound Element

MIXTURE PURE SUBSTANCE

yes no

Can it be decomposed by chemical means?

noyesIs the composition uniform?

noyes

Section 2.1 Classifying Matter

Solutions, Suspensions, and Colloids The size of the particles in a mixture has an

effect on the properties of the mixture. Key Concept: Based on the size of its

largest particles, a mixture can be classified as a solution, a suspension, or a colloid.

Section 2.1 Classifying Matter

Solutions Def.-the mixture that forms when substances

dissolve and form a homogeneous mixture Ex. Sugar water, salt water,

lemonade

Section 2.1 Classifying Matter

Solutions *They do not separate into distinct layers

over time. *They cannot be filtered. *Light passes through them. The particles in a solution are too small to

settle out of the solution, be trapped by a filter, or scatter light.

Section 2.1 Classifying Matter

Suspensions Def.-a heterogeneous

mixture that separates into layers over time

Ex. Amoxicillin, Muddy water, Flour suspended in water

Section 2.1 Classifying Matter

Suspensions *Suspended particles settle out of a mixture

or are trapped by a filter They scatter light in all directions because

the particles are large; suspensions are cloudy.

Section 2.1: Classifying Matter

Colloids Def.-a mixture that contains some particles

that are intermediate in size between the small particles in solution and larger particles in a suspension

Ex. Milk, fog

Section 2.1 Classifying Matter

Colloids Do not separate into layers Cannot be filtered Since they also contain larger particles, they

scatter light

Matter Flowchart

MATTER

Can it be separated by physical means?

Homogeneous Mixture

(solution)

Heterogeneous Mixture Compound Element

MIXTURE PURE SUBSTANCE

yes no

Can it be decomposed by chemical means?

noyesIs the composition uniform?

noyes