Science Test

Definitions:

• Pure substances: made up of only one kind of particle and have a fixed or constant structure

• Elements: a chemical substance that cannot be broken down into other substances by chemical reactions

• Compounds (Ionic vs Molecular): a substance made from two or more different elements that have been chemically joined

• Atoms: the basic particles of the chemical elements

• Molecules: two or more atoms bonded together

• Ions: an atom or group of atoms that has an electric charge

• Heterogeneous mixture: you can see lumps of each component

• Homogeneous: the individual components are not visible 

Physical/Chemical properties: methods of description, length vs flammability

Physical/Chemical change: physical the shape or look changes. In chemical the substance changes. 

Separation techniques: distillation, filtration, evaporation, decanting

Solutions (ionic vs molecular): Molecular compounds are made due to covalent bonding, while ionic compounds are made due to ionic bonding.

Diatomic elements: hydrogen (H), nitrogen (N), oxygen (O), fluorine (F), chlorine (Cl), bromine (Br), and iodine (I)

Factors affecting solubility: temperature, pressure, polarity, and molecular size

• Solid in liquid

• Gas in liquid

Solubility curves

Unsaturated: a solution that can dissolve more solute

Saturated: cannot dissolve more solute

Supersaturated: has more solute dissolved than it is supposed to 

Atomic notation: mass number, symbol, atomic number

Protons: nucleus, mass 1, charge 1

Electrons: outside, mass 0, charge -1

Neutrons: nucleus, mass 1, charge 0

Phases of matter:

• Solid: fixed shape, not compressible

• Liquid: takes shape of container, not compressible

• Gas: takes shape of container, compressible

• Aqueous: has been dissolved in water

Precision: measures how close results are to one another

Accuracy: measures how close results are to the true or known value

Calculating density: density = mass / volume

Scientific notation: 0.000073=7.3 times 10 to the -5