Chemistry Chapter 1

Atoms and examples

Smallest, chemically invisible particles of matter - neutral

examples: helium, neon, gold, mercury

Molecules and examples

Smallest chemical entities that can exist discretely in nature

• may constitute one or more atoms

examples: neon, oxygen, hydrogen, chlorine, sulfur, water

Ions and examples

charged entities formed by gaining or losing electrons

• may constitute on or more atoms

examples: sodium ion, chloride ion, sulfate ion

Pure substance

made up of only 1 component and composition is fixed
- substances are divided into elements or compounds

Mixture

composed of 2 or more chemically distinct components with varying proportions

Heterogenous

the components can be identified with the naked eye or a microscope

sample of blood, milk, salt/sand mix

Homogenous

components can’t be identified with naked eye or microscope, its components mix uniformly

air, solution of sugar and water

Decanting

waiting until sand settles at the bottom of a mix, then pouring water into other container

Filtration

filters such as sponge or canister filters

Distillation

process in which mixture is heated to boil off the ethanol (easily vaporizable liquid)

Example of physical changes

water boiling

Example of chemical changes

nail exposed to air or moisture and rusts

Examples of physical properties

smell of gas, odor, taste, color, appearance, melting point, boiling point, density

Examples of chemical properties

flammability of gas, corrosiveness, acidity, reactivity, toxicity

Energy

the capacity to do work

example of energy release

combustion of gasoline releases energy, which moves a car

example of energy absorption

photosynthesis in plants absorbs energy

Forms of energy and what they relate to

Kinetic - motion

Potential - position

Mechanical - movement

Thermal - temp/heat

Chemical - reactions

Metric system units

cm, m, kg, g, L, mL. km

English system

in, ft, yd, lb, gal, mi

SI base quantity and units

length - meter

mass - kilogram

time - second

temp - kelvin

amount of substance - mole

electrical current - ampere

luminous intensity - candela

Sig fig rules

1. all non zero digits are significant

2. interior zeros are significant

3. leading zeros are not significant

4. trailing zeros after a decimal are significant

multiplication/division rule

result should have the same number of sig figs as the number with the least sig figs

addition/subtraction rule

the result should have the same number of decimal placesa as the number with the least decimal places

accuracy

how close the measaured value is to the actual value

precision

how close or consistent a series of measurements are to one another