Chemistry Regents Unit 1

Substance

form of matter with constant chemical composition and properties

Mixture

two substances that were mixed physically (not chemically bonded)

Compound

two substances that were chemically combined

Homogeneous mixture

mixture components are evenly distributed

Heterogenous mixture

mixture where the components are not evenly distributed and are easily distinguishable

Solutions are always _____

Homogenous

Kelvin to celcius

Celcius = Kelvin - 273

Charge of an atom’s nucleus

positive

Electron’s charge

negative

Orbitals

areas where an electron with a certain amount of energy is most likely to be found

Where are protons and neutrons found?

in the nucleus

Charge of protons

positive

Charge of neutrons

0 (no charge/neutral)

The number of protons in an atom equals:

the number of electrons

Mass of a proton

1 amu

Mass of a neutron

1 amu

Mass of electron

~0 amu

Atomic mass

number of protons + number of neutrons

Ground state

when all electrons are at their lowest possible energy (as shown in reference table)

Bright line spectrum

formed when a electron returns from a higher energy state to a lower energy state

Valence electrons

electrons in the outermost shell

Atomic number

number of protons in an element

Isotpoes

atoms with the same atomic number (protons only) but different atomic masses (protons + neutrons)

Average atomic mass of an element

weighted average of its naturally occurring isotopes