Chapter Two

Properties of Matter

Classification of Matter

Matter• Is anything that has mass and takes up space

•In its most basic distinction, matter can be classified as either a

pure substance or a mixture.

Pure Substance• Like the name suggests, a pure substance is

made of one type of material. It cannot be broken down into a simpler form without

losing its identity.

Elements• Elements are the simplest form of a

pure substance. They are only composed of atoms of that element.

• Gold is only made up of gold atoms.

• Chlorine is only made up of atoms of chlorine.

• Sulfur is only made up of atoms of sulfur.

Elements

• Prepare for Element Quizzes!!!!!!• You will know them inside and out!!!

• Elements

• All atoms of an element are identical to each other but completely different from atoms of any other element.

• Each atom of a given element has a unique number of protons in its nucleus. This determines the identity and the properties of that element.

• Every element is identified by a chemical symbol, a 1,2,or 3 letter symbol taken from the element’s name (Latin), country of origin, or the person who discovered it. – There have been over 120 identified elements, 92 of

which are naturally occurring . • Elements cannot be broken down into any

simpler substance.

Properties of Elements

Daily Assignment

• Explain why both elements and compounds are considered pure substances.

• Each are only made up of only one type of substance.

• Elements are composed of atoms of that element.

• Compounds are composed of molecules of that compound.

Compound• Are formed from the chemical combination of

two or more elements. • To create a compound, a chemical change ( or

reaction) must take place in which a new substance with a new set of properties is formed.

Sodium + Chlorine Sodium Chloride

Properties of Compounds• Chemically combined groups of elements are called

molecules, represented by a chemical formula. – The formula tells you the identity of the elements and the number of

atoms of each element in that compound. NaCl H20 NH3 Each molecule of a given compound is identical to every molecule of that

compound, but completely different from molecules of a different compound.

• The properties of the compound are different than the properties of the elements that make it up. – NaCl is table salt. It is formed by the chemical combination of Na, a

silver metal that explodes in water and Cl, a poisonous green gas. – Sucrose (C12H22O11 ) is table sugar. However, Carbon is a black

solid and hydrogen and oxygen are both colorless, odorless gases.

Compounds• The ratio of different atoms in a

compound is always the same. Hydrogen and oxygen can combine in different ratios to form

different compounds.

• Compounds cannot be broken down into simpler substances that still retain the properties of that compound.

H2O H2O2

Daily Assignment

Copper, Sulfur ,

and oxygen combine to create

Copper sulfate.

• How do you know that copper sulfate is a compound?

Mixture• Matter that consists of two or more

substances that are mixed together but not chemically combined is a mixture. Mixtures

are physically combined.

Mixtures “together but separate”

Mixtures• Each substance that makes up

a mixture retains its chemical / physical properties.

Sulfur = yellow, rotten egg smell

Iron = black, magnetic

Even in a mixture, iron is still magnetic.

Iron in the compound FeS is NOT magnetic.

Mixtures• The substances that make up a mixture

may be present in any amount, unlike compounds which must combine in

specific ratios.

It doesn’t matter how much koolaid you mix with the water, it is always a koolaid and water mixture.

Mixtures• Since mixtures are physically combined they

can also be separated based on the physical properties of their components.

• How would you separate these mixtures?

Ocean water Beach sandTrail mix

Separation of Mixtures

Mixtures

• Mixtures can be further distinguished as either a homogeneous mixture or a

heterogeneous mixture.

Homogeneous Mixture

• A.K.A. a solution. “Homo” means the same. A homogeneous mixture appears to have the same properties throughout the entire mixture.

• A solution is formed when substances are dissolved in another substance. The particles that make up a solution are very small. They will never settle to the bottom.

PURE AIR

Heterogeneous Mixture

• Is a mixture that appears to have “different” properties throughout the mixture. The particles that make up a het. mixture are larger then those that make up a solution.

What kind of mixtures are these?

Colloid

• The particles that make a colloid are mixed, but not dissolved. These particles are larger than those in a solution, but they will never

settle to the bottom.

• Due to their large particle size, a colloid often appears cloudy.

Mayonnaise paint milk smog Jello and whipped cream

Suspension

• Are the least mixed of all the mixtures. These are made of the largest size particles. If you

let a suspension sit long enough, it’s particles will settle to the bottom.

Cookie dough ice cream

Cereal and milk

Muddy pond water

Tyndall Effect• Is the effect of a laser to pass through a

mixture. • If the laser passes through completely, the

mixture is a solution. • If the laser is trapped (or bounced between

particles) it is a colloid or suspension.

Light passes through the blue solution.

Particles of a colloid scatter the light

Physical Properties• A physical property is a

characteristic of material that you can observe without changing the identity of the substances that make up the material.

• Examples: color, shape, size, density, melting/freezing/boiling point, texture, magnetism, and viscosity .

Physical Properties

• Viscosity – the tendency of a liquid to resist flow

• Conductivity – the ability of a substance to carry electrical current

• Malleability – the ability of a substance to bend without breaking

• Hardness – How hard something is• Melting and Boiling Points

Physical Properties• Density – ratio of a substance’s mass to

its volume• Two ways to separate mixtures– Filtration – using some kind of medium to

remove large particles– Distillation – boiling out the pure substance

Physical change• A change is the size, shape or state of matter.

• The identity of the materials that makeup the substance is never altered during a

physical change.

Chemical Property• A chemical property is a characteristic of a

material that you can only observe by changing the identity of the substance.

flammability

Photosensitivity Oxidation (rust)

combustibility

Chemical Properties• Flammability – the readiness with which a material burns• Reactivity – the likelihood of something reacting with

another chemical

• Chemical Properties

Chemical Change• A changing of one substance to another is a

chemical change. You cannot return to the original substance after a

chemical change.

Fizzing and bubbling indicate chemical change. Cooking is a

chemical change

Electrolysis: separation of

water

Chemical Changes• Evidence of a chemical

change– Change in color– Production of a Gas• See Demonstration

– Formation of a Precipitate• See Demonstration

Chemical Vs. Physical

• In a chemical change, the substance changes. In a physical change, the matter remains the same.