SAAT Chemistry Section 1 (Introduction to Chemistry) - تحصيلي

Chemistry

The study of matter and the changes that it undergoes

Troposphere

Nearest layer to the earth

Stratosphere

Second layer after troposphere; where the ozone layer is located

Ozone hole

Part of the atmosphere thinning over Antarctica as a result of the reaction between ozone and chlorofluorocarbones

What the ozone layer does

Protects the earth from harmful rays such as ultra violet rays

Matter

Anything that has mass and takes up space

Mass

The amount of matter in an object

Branches of chemistry

Organic chemistry, inorganic chemistry, physical chemistry

Where matter can be found

Solid, liquid, gaseous, or in plasma state

Solid

A form of matter that has its own definite shape and volume

Liquid

A form of matter that flows, has constant volume, and takes shape of the container

Gas

A form of matter that not only takes shape of the container, but also fills the entire volume of the container

Plasma

A form of matter that is present in places with very high temperatures

Vapor

A gaseous state of a substance that is solid or liquid in room temperature

Physical property

A characteristic of matter that can be observed or measured without changing the composition of the sample

Two types of physical properties

Extensive and intensive

Extensive properties

Dependent on the amount present in a substance such as mass

Intensive properties

Independent on the amount present on a substance such as density

Chemical property

The ability or inability of a substance to combine with or change into one or more other substances

Physical change

A change that changes the substance without changing its composition like cutting a sheet of paper, melting, or freezing

Chemical change

A process that involves one or more substances changing into new ones like burning or rusting

Evidence of chemical reactions

A change in color, taste, elimination of gas, or a precipitate

Law of conservation of mass

States that the mass is neither created nor destroyed during a chemical reactions

mass of reactants = mass of products

Mixture

A combination of two or more pure substances in which pure substance retains its individual chemical properties

Heterogeneous mixture

One that does not blend smoothly throughout and in which the individual substance remains distinct

Homogenous mixture

One that has constant composition throughout; it always has a single phase

Suspension

Mixture containing particles that settle out if left undisturbed

Colloid

A heterogenous mixture that has particles of sizes between 1 nm and 1000 nm in diameter and do not settle out

Brownian motion

The random movement of liquid colloid particles

Tyndall effect

The scattering of light due to the dispersed colloid particles

Solution

A homogenous mixture from two or more substances

The processes used to separate mictures are physical process that are based on

The differences in the physical properties of the substances

Filteration

A technique that uses a porous barrier to separate insoluble solid from a liquid

Distillation

A physical separation technique that is based on the differences in the boiling points in the subustances involves

Crystallization

A separation technique that results in the formation of pure solid crystals of a substance from a substance from a solution containing the dissolved substance

Sublimation

The process during which a solid changes into vapor without melting; it can be used to separate two solids in a micture when one of them sublimates without the other like dry ice

Chromatography

The technique that separates the components of a mixture dissolved in either a gas or a liquid based on the distinctive attraction to the mobile phase and a stationary phase

Element

A pure substance that cannot be separated into simpler substances by physical or chemical means

Compound

A pure substance made up of two or more different elements that are combined chemically

Law of definite properties

States that a compound is always composed of the same elemens in the same proportions by mass, no matter how large or small the sample

Law of multiple proportions

States that when different compounds are formed by a combination of the same elements, different masses of one element combine with the same fixed mass of the other element in a ratio of small whole numbers