Chemistry Definitions

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Chemistry Definitions

Classification of Matter

A flowchart with examples

What the particles would look like

Mixtures

Can be separated by physical means

Made up of more than one kind of molecule

Heterogenous Mixture (mechanical mixture): A mixture where more than one substance is visible. ex. compost

Homogeneous Mixture (Solution): Particles mix well with each other, so well that you can only see one phase or visible part. ex. salt mixed into water

Compound: Pure substances that contain two or more different elements formed for a chemical reaction

Can be broken down by chemical means

Made up of more than one kind of atom

Element: Pure substances that can be broken down into simpler substances

Cannot be broken down by chemical means

Made up of only one type of atom

Pure substances: A substance that contains only one type of particle

Matter: Anything that has a mass and takes up space (it has a volume)

Molecules: Pure substances where the atoms combining can be the same or different. ex. O2, H2O

Bohr-Rutherford Diagram

An example of what the Bohr-Rutherford Diagram looks like

On the energy levels, there are the electrons that orbit around the nucleus. 2 on the innermost shell (level) and 8 on all the others

Each row (called periods on the periodic table) have the same number of energy levels as the number of row they're in

Example: Period 1 (hydrogen and helium) have one energy level where the electrons orbit around the nucleus

Energy levels are called shells

Picture of definitions on the periodic table

Atomic Number

The number of protons in the nucleus (same number of electrons)

Smaller of the two numbers

Element Symbol

The symbol used to identify an element (eg. Co for Cobalt)

Mass Number

The mass of an atom of that element

The bigger of the two numbers. Used to find number of neutrons

How To Get Mass Number

Mass number = atomic number + number of neutrons

How To Find Number Of Protons, Neutrons, and Electrons

Number of Electrons: same as number of protons

Number Of Neutrons: Atomic Mass subtracted by Atomic Number

Number of Protons: Atomic number

Hydrogen

Grouped with alkali metals but does not have the same properties

Behaves like a non metal

Metalloids

Elements that posses both metal and nonmetal properties

Found on the "staircase"

Halogens

Examples: Fluorine, Bromine, Chlorine

Like to form salts

Have 7 electrons in their outer orbit

Most reactive nonmetals

Occupy the 17th column

Alkaline Earth Metals

Examples: Magnesium, Calcium Barium

React with acids

Have two electrons in their outer orbit

Reactive but not as reactive as alkali metals

Occupy the 2nd column

Alkali Metals

Examples: Lithium, Potassium, Sodium

Release hydrogen when mixed with water

Have 1 electron in their outer orbit

Are extremely reactive

Occupy the 1st column

Noble Gases

Examples: Neon, Argon, Helium

Don't form compounds

Have a stable electron configuration (8 electrons)

All are unreactive

All gases are room temperature

Found at the far right of the table

Electrons

Orbits around nucleus

Almost 0 amu (atomic mass unit)

Negative charge

Protons

Positive charge

Neutrons

How To Get Number Of Neutrons

neutron number = mass - atomic number

found in nucleus

1 amu (atomic mass unit)

Neutral charge