Chapter 2 Section 1 Notes

What is Matter?

Chemistry

Chemistry: The study of matter and how it changes

Examples of how we use chemistry everyday: Cell phones soap food clothes

Matter

Matter: anything that has mass and takes up space

Examples of matter: people rocks air

The following are NOT matter because: they have no mass & don’t take up space light sound electricity time

Elements

Elements: substances that cannot be broken down into simpler substances

Examples: Helium Silver Neon

If it is on the PERIODIC TABLE of the ELEMENTS, it’s an element!

Elements are made up of atoms.

Atoms: smallest particle of an element that still has properties of an element

Examples of substances made of atoms of the same element: Diamonds: made of carbon Foil: made of aluminum

Elements on the Periodic Table:

In 1760, there were only 16 known elements because scientists at the time weren’t clear of the nature of gases. Each element has its own symbol, made up on one or two letters. If there are 2 letters, the first one is ALWAYS capital and the second is ALWAYS lowercase. The current standard table contains 118 confirmed elements. Each element behaves differently & uniquely from each other.

Examples:

Hydrogen: HCarbon: COxygen: OSodium: NaGold: Au

Compounds

Compounds: substances made of atoms of more than 1 element joined together.

Examples: Sugar: C12H22O11: Made of the elements

carbon, hydrogen, and oxygen. Human Body: contains oxygen, nitrogen,

sulfur, phosphorus, hydrogen, etc. (Most of the elements exist as compounds instead of as free elements floating in the body.)

Compounds

Every compound is unique and different from the elements it is made from. Think of NaCl.

Picture of Sodium metal

Picture of Chlorine gas

Picture of table salt

Molecules

Molecules: smallest unit of a compound that still behaves like the compound.

Examples:Water, H2O, is 1

molecule of water; if you take away an atom of hydrogen or oxygen, it is no longer water.

Oxygen, O2 molecules can also be made of atoms of the same element O2 is called a diatomic

molecule

Chemical Formula

Chemical Formula: the chemical symbols and numbers indicating the atoms contained in the basic unit of a substance.

Subscripts

Subscripts: tells the number of atoms of each element in a compound.

Examples: H2O water, contains 2 hydrogen atoms and 1 oxygen

atomCO2 carbon dioxide, contains 1 carbon atoms and 2

oxygen atomsC3H8O rubbing alcohol, contains 3 carbon atoms, 8

hydrogen atoms, and 1 oxygen atom.3CO2: the number in front is called a coefficient and

tells how many molecules there are of that compound.

Pure Substances

Pure substance: any matter that has a fixed composition and definite properties

There are 2 types of pure substances:1. Elements

2. Compounds

Pure Substances

Examples of pure substances: Carbon – element Methane, CH4 – compound

Silver – element Neon – element Carbon dioxide, CO2 – compound

Water, H2O - compound

Mixtures

Mixtures: a combination of pure substances; can be physically separated into parts

Examples salad: can separate lettuce, tomato, onion grape juice air we breathe: 78% Nitrogen, 21% Oxygen

(other 1% carbon dioxide, argon, helium, and neon)

There are 2 types of mixtures:

1. Homogeneous mixtures: mixtures that are uniformly mixed

Examples: salt water, kool-aid, air we breathe

We say that homogeneous mixtures are miscible, which means solids, liquids, or gases that can be mixed

There are 2 types of mixtures: (continued)

2. Heterogeneous mixtures: mixtures that are NOT uniformly mixed

Examples: flour and water, Italian dressing

We say that heterogeneous mixtures are immiscible, which means they don’t completely mix, can often see layers

Graphic Organizer for Matter

Matter

Pure Substances Mixtures

Elements CompoundsHomogeneous

MixtureHeterogeneous

Mixture