Chemistry Chapter 4

Chemistry

the study of matter and the changes it undergoes

Matter

anything that has mass and takes up space

Pure substance

matter that has a definite composition, a chemical formula

Element

pure substances that cannot be broken down into simpler substances by physical or chemical means

Atom

the smallest particle of an element that retains all the properties of the element

Modern Atomic Theory

All matter is composed of small, divisible particles called atoms. Not all atoms of the same element are identical (isotopes). Atoms of different elements are different. Atoms can bond with one another in simple ratios to form compounds.

Subatomic particles

particles smaller than atoms (proton, neutron, electron)

Atomic mass unit

unit of mass for expressing masses of atoms or molecules; 1/12 of the mass of an atom of carbon-12

Nucleus

located in the center of the atom, small in volume, positively charged, contains most of the atom's mass

Electrostatic attraction

the attraction between oppositely charged particles (negative electrons to positive protons)

Electron

symbol: e-, charge: 1-, mass: 0 amu, location: empty space around nucleus/ electron cloud

Proton

symbol: p+, charge: 1+, mass: 1 amu, location: nucleus

Neutron

symbol: n0, charge: 0, mass: 1 amu, location: nucleus

Atomic number

the number of protons in an atom, symbol: Z, whole number located in the box, makes an element a particular element.

Isotopes

atoms with the same number of protons, but different numbers of neutrons, same element that differ in mass number

Mass number

the sum of the number of neutrons and protons in an atomic nucleus, symbol: A, NOT on most periodic tables

Atomic mass

the weighted average mass of the naturally occurring isotopes of an element, (%)(mass) + (%)(mass) + ...

Radioactivity

the spontaneous emission of radiation

Radiation

energy rays and/or particles

Radioactive decay

to fall apart by giving off nuclear radiation, until they become stable

Ratio of neutrons to protons

what determines the stability of an atomic nucleus

Nuclear reaction

the atom's nucleus changes, often turns into a different element

Nuclear equation

symbolizes a nuclear reaction

Alpha radiation

helium-4, consisting of 2 protons and 2 neutrons, mass: 4 amu, charge: 2+

Beta radiation

a high-speed electron emitted from a radioactive nucleus, mass: 0 amu, charge: 1-

Gamma radiation

a high-energy form of electromagnetic radiation, has no mass and no charge, not a particle, just energy

Fission

a neutron slams into a larger atom, forcing it to split into two smaller atoms (splits)

Fusion

two atoms slam together to form a heavier atom (fuse)

Law of Conservation of Mass-Energy

mass and energy can be converted from one to the other, but their sum remains constant

Circle graph

shows the parts of a whole/ percentages

Bar graph

evaluates trends in a measured property often as a function of time, location, or temperature

Line graph

determines property trend or the mathematical relationship between two variables

Direct relation

positive slope, straight line

Indirect relation

negative slope, straight line

Inverse relation

hyperbola, a curve with a negative slope that never crosses an axis