Matter 2025 atoms, elements, compounds, and the Periodic Table

matter

anything that has mass and occupies space (volume)

atom

the smallest unit of an element that has all of the properties of that element

element

a pure substance made of only one kind of atom / the building blocks of matter

properties

characteristics used to describe a substance

physical properties

a characteristic of a substance that can be observed or measured without changing the identity of the substance

chemical properties

the ability to change into a new substance with different properties

density

measure of the amount of mass in a given volume

electrical conductivity

measure of how well a current can move through a substance

thermal conductivity

rate at which a substance transfers heat

solubility

the ability of a substance to dissolve in another substance

malleability

the ability of a substance to be rolled or pounded into shapes

luster

shine / the way something reflects light

melting point

temperature at which a substance changes from a solid to a liquid

boiling point

the temperature at which a substance changes from a liquid to a gas

flammability

the ability to burn

reactivity

the ability of a substance to interact with another substance to produce one or more new substances

protons

subatomic particles that have a positive charge

electrons

subatomic particles with a negative charge / the smallest subatomic particle

neutrons

subatomic particle with no charge

atomic number

the number of protons in the nucleus of an atom

nucleus

the center of an atom that contains the protons and neutrons

mass

the amount of matter in an object

orbital

the region around the nucleus of an atom that contains electrons

chemical symbol

an abbreviation that represents an element

isotope

an atom with the same number of protons and a different number of neutrons from other atoms of the same element.

chemical symbol

abbreviation that represents an element

metals

elements that are good conductors of electric current and heat, malleable, and usually solid

nonmetals

poor conductors of heat and electric current, lack luster, usually gases, and brittle

brittle

easily broken; not flexible

metalloids

elements that have properties of both metals and nonmetals (semiconductors)

atomic weight / atomic mass

average of the mass numbers of all isotopes

period

a horizontal row of elements on the periodic table

family or group

a vertical column on the periodic table

conductor

a material that allows heat and electricity to pass through it.

horizontal

side to side

vertical

up and down

ductile

a material that can be pulled out into a wire.

solids

have a definite volume and a definite shape/ the particles vibrate, but they are fixed in place

liquids

definite volume, but no definite shape / particles are close together and slide past each other

gas

no definite volume no definite shape / particles are not close together and move in any direction

Kinetic Theory of Matter

all matter is made of atoms that are in constant motion

sublimation

the process in which a solid changes directly into a gas

deposition

the process in which a gas changes directly into a solid

vaporization

the change from a liquid to a gas (boiling or evaporation)

boiling

vaporization that occurs on or below the surface of a liquid

evaporation

vaporization that takes place only on the surface of a liquid

molecules

two or more atoms joined together (the same or different elements)

compounds

2 or more different elements chemically combined

positive ion

created when an atom loses an electron

negative ion

created when an atom gains an electron