Matter and atoms Flashcards
Matter
Anything that takes up space and has mess
Atom
Indivisible, generally refers to the one individual particle of the smallest unit of matter
Pure substance
Only made of one type of material e.g helium gas
Mixture
Made of 2 or more different substances which can be separated by physical means (not chemically joined) e.g blood
Categories of pure substances
Elements
Molecules
Compounds
Elements
A substance made up of only one type of atom
Molecules
A substance made up of two or more atoms which are either from the same element or different elements e.g O2 or CO2
Compounds
A substance made up of two or more atoms which are from different elements e.g CO2
States of matter
Solid
Liquid
Gas
Solids characteristics
Have a definite shape Occupy definite volume Forces are strong Atoms aren't moving much Molecules lock into place and form a rigid structure that maintains fixed volume and shape Regularly arranged particles
Liquids Characteristics
Occupy a definite volume
No defined shape
Lower force of attraction between molecules
Molecules have more energy/moving more
Forces of attraction still keep molecules stuck together but the can slide across each other
Randomly arranged particles
Gas Characteristics
Doesn’t have a definite shape
The molecules have so much energy and moving so fast they break the forces of attraction that want to keep them together
Large amount of space between the molecules means that gases do not have a defined volume (Gases expand or compress to fit the space they are in)
Randomly arranged particles that can move in all directions
State of a substance at room temp is determined by…
Forces of attraction between molecules
Molecules vibration
(low vibration = pack together and low temp)
Heat
The movement of atoms
Components of atoms
Nucleus which contains neutrons and protons
Electrons in shells
Mass number
The sum of protons and neutrons in the nucleus
Isotopes
An atom of a particular element that has a different number of neutrons which changes mass number only
Atomic mass
An average of the number of protons and neutrons found in nature (includes isotopes)
Capacity of electron shell 1,2,3
1 = 2 electrons 2 = 8 electrons 3 = 8 electrons
Octet rule
The tendency of atoms to prefer to have 8 electrons in their second and third shell
Valence shell
Refers to the outermost electron shell that actually contains electrons
