Elements, Compounds, and Mixtures

3 STATES OF MATTER Solids Liquids Gases

3 KINDS OF MATTER Elements Compounds Mixtures

Elements All matter is made from about 100 different substances, called elements. Elements are called the building blocks of matter because all matter is composed of elements. Each element is made up of the same type of atoms.

Compounds A compound has properties different than the elements that make it up. The parts of a compound are present in a specific ratio. The symbols make up the formula. A formula is just chemical shorthand for the compound.

Compounds continued The subscript (bottom number) lets us know how many atoms are present. The coefficient (front number) lets us know how many molecules are present. No number in either location indicates only one atom.

Compounds and continued again A compound is a substance made of two or more different kinds of elements chemically combined in a specific ratio. Each compound is represented by a formula that uses symbols to identify which elements are present. A formula shows the ratio of elements in the compound. H2O – ratio of Hydrogen is 2:1 Oxygen

Molecule The smallest bit of each of these substances would be referred to as a molecule. For example, a single molecule of molecular hydrogen is made from two atoms of hydrogen. A single molecule of water is made from two atoms of hydrogen and one atom of oxygen.

Molecules A molecule is formed when two or more atoms join together chemically. Diatomic molecules are made of two atoms of the same element. Hydrogen – H2 Oxygen – O2 Nitrogen – N2

What is the difference between a compound and a molecule? A molecule is formed when two or more atoms join together chemically. A compound is a molecule that contains at least two different elements. All compounds are molecules but not all molecules are compounds.

Molecule When a compound is broken down into its’ smallest piece it is called a molecule. You should be able to write the formula for the following: Hydrogen Oxygen Nitrogen Water Carbon Dioxide Sodium Chloride

Molecules vs. Compounds Molecular hydrogen (H2), molecular oxygen (O2) and molecular nitrogen (N2) are not compounds because each is composed of a single element. Water (H2O) and Carbon dioxide (CO2) and Sodium Chloride (NaCl) are compounds because each is composed of 2 or more different elements.

Water is H2O An oxygen atom can bond with two hydrogen atoms to make a molecule we call water. Water is an example of a compound, because it contains more than one kind of atom. The formula for water is H2O, meaning there are two hydrogen atoms for each oxygen atom.

Carbon Dioxide CO2 A carbon atom can bond with two oxygen atoms to make a molecule we call carbon dioxide. Carbon dioxide is an example of a compound, because it contains more than one kind of atom. The formula for carbon dioxide is CO2, meaning there are two oxygen atoms for each carbon atom.

Sodium Chloride NaCl One sodium atom can bond with one chlorine atom to make a molecule we call sodium chloride (table salt). Salt is an example of a compound, because it contains more than one kind of atom. The formula for water is NaCl, meaning there is one sodium atom for each chlorine atom.

Mixtures Most matter in the universe is found in mixtures. A mixture is made from two or more substances either elements, compounds or both - that are not chemically combined.

Compounds and Mixtures Most of the matter around you is in the form of compounds or mixtures. Water, carbon dioxide, salt, vinegar, baking soda, lye, sugar, gasoline, and bleach are all examples of compounds.

Compounds and Mixtures A mixture is a substance in which different materials can be easily distinguished Pizza, soup, fruit salad, Chex mix, trail mix, granola are all examples of mixtures.

Solutions Solutions are special type of mixtures. The Solute is the substance being dissolved. The Solvent is the substance that dissolves the solute. Solubility is the amount of a solute that will dissolve in a solvent.

Example Water is called the universal solvent. (Salt water is an example of a solution). Salt dissolves in water so NaCl is the solute. Water dissolves salt so H2O is the solvent.

Colloids and Suspensions A colloid is a homogeneous mixture that like a solution never settles. One example of a colloid is milk. Milk has evenly distributed particles that scatter light and never settle.

Suspension A suspension is a heterogeneous mixture containing a liquid in which visible particles settle. One of a suspension is dirty river water. example. River water has large enough particles that do settle.