Matter Notes Continued

Chemistry The study of how matter changes.

Elements A substance that cannot be broken down into any other substance by chemical or physical means. Building blocks of matter because all matter is composed of elements.

Compounds and mixtures Compound – a substance made up of two or more elements combined in a specific ratio. –Example: CO 2, H 2 O –Formula – combination of symbols that shows the ratio of elements in a compound Mixture – consists of two or more substances that are in the same place together but are not chemically combined into a new substance. –Example: muddy water, chocolate milk, air

Physical vs. Chemical changes Physical change – alters the form of a substance but does not make the material into another substance. –Example: ripping paper, phase changes Chemical change – a change in matter that produces new substances. –Example: burning paper, rust on a car

John Dalton Greek philosopher and school teacher around 440 BC Proposed the atomic theory which states: –Atoms cannot be broken into smaller pieces –In any element, all the atoms are exactly alike –Atoms of different elements are different –Atoms of two or more elements can combine to form compounds –Atoms of each element have a unique mass –The masses of the elements in an compound are always in a constant ratio

Chemical bonds and molecules Chemical bond – the force that holds two atoms together Molecule – A combination of two or more atoms that are bonded together.

Amorphous vs. Crystalline Solids Amorphous solid – do not have a distinct melting point and are not arranged in a regular pattern –Examples: plastics, rubber, glass Crystalline solid – form a regular repeating pattern and have a distinct melting point –Examples: salt, sugar, sand, snow

Pressure Pressure = Force/Area Pressure is measured in kilopascals (kPa).

Boyle’s Law The relationship between the pressure and volume of a gas at constant temperature; when volume increases, pressure decreases. Temperature Volume Pressure

Charles’s Law The relationship between the temperature and volume of a gas at constant pressure; when temperature increases, volume increases. PressureTemperatureVolume

Archimedes’ Principle The rule that the buoyant force on an object is equal to the weight of the fluid displaced by the object. –Example: a boat pushes down with the same force that that water pushes up.

Pascal’s Principle The rule that when force is applied to a confined fluid, the increase in pressure is transmitted equally to all parts in the fluid. –Example: squeezing a water bottle increases the pressure of the entire bottle no matter where you squeeze it.

Graphing Gas Behavior Directly proportional – when a graph is a straight line passing through the (0, 0) point. Example: Charles’s Law Vary inversely – when a graph forms a curve. –Example: Boyle’s Law

Latent Heat When you have a phase change, there is NO change in temperature. –Ex: when water is melting, it stays at 0 degrees Celsius until all the water melts –Ex: when water is boiling, it stays at 100 degrees Celsius until all the water boils away