Exam Study Guide: Science

Weight

• The pull of gravity on an object

• Changes depending on location

Mass

• The measurement of the amount of atoms in an object

• Always consistant

Volume

The amount of space an object takes up

Density

The measure of the amount of matter in a defined amount of space

Unit

A fixed amount of something; centimeter of distance for an example

SI

International System of Units

Matter

Anything that takes up space and has mass

Physical properties

Any characteristic of matter that can be observed without changing its composition

Chemical properties

A characteristic of a substance that can’t be observed without altering the chemical composition

Chemical change

The change of one substance to another; these changes cannot be reversed

Physical change

A change in the physical properties of a substance

Law of conservation of mass and matter

The mass of all substances before a chemical or physical change must equal the mass of the substances after the change

Atomic number

The number of protons and electrons in an atom

Ion

An atom that has an electrical charge because it stole or gave away electrons

Compounds

2 or more different elements chemically bonded to form a new substance

Bonds

Pooling between metals, sharing of all electrons

Motion

A change in position for an object

Speed

Describes how quickly an object is going

Velocity

Speed and direction

Solids

• Atoms are vibrating and touching

• F of A is super strong

• Definite volume and shape

Liquids

• Atoms are touching and sliding past each other

• F of A is not as strong

• No definite shape; definite volume

Gas

• atoms are free

• no F of A

• No definite shape or volume

Plasma

• When electrons are stripped from the atom

• Really hot or cold

• Dense or wispy

AVG atomic mass

the average atomic mass of all the isotopes of an atom

Atomic mass

The number of protons and neutrons in an atom

Substance

matter that has the same composition and properties throughout

Mixture

matter made up out of 2 or more substance that are not chemically combined

Homogeneous

A mixture that is evenly spread out

a mixture where substances are unevenly spread out

Neutral atom

An atom that has the same # of protons and electrons

Stable atom

have a full outer electron shell or 8 outside ones

Pooling

• Between metals

• Sharing of all electrons

• When atoms hold valence electrons so loosely they are able to flow between atoms

• C=C

Covalent bonds

• Between non metals

• Sharing with 2 or less atoms

Polar molecule

• Molecule with slight uneven charge

• Uneven sharing of electrons

Molecule

• Atoms of the same or different elements chemically combined by sharing electrons

• Covalent bonds

Factors determining motion

• Reference point

• Distance- how far the object travels

• Time- how long to travel distance

• Direction of motion

Constant speed

• This speed doesn't vary

• Stays the exact same

• EX: Earth's spin

AVG speed

• Distance/ time it took to travel

• Not constant