Compounds , Mixtures and Collides

Muhammad Fahad Ansari 12IEEM14

3 KINDS OF MATTER

ElementsCompoundsMixtures

Elements

All (living and nonliving) of the different kinds of matter in the universe 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 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

The symbols make up the formula. A formula is just chemical shorthand for the compound.

The subscript lets us know how many atoms are present.

The coefficient lets us know how many molecules are present.

CompoundsCompounds

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

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.

Molecular hydrogen (H2), molecular oxygen (O2) and molecular nitrogen (N2) are not compounds because each is composed of a single element.

Water (H2O), carbon dioxide (CO2) and methane (CH4) are compounds because each is made from more than one element.

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.

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.

Mixtures and compounds differ

in two ways…

Substances in a mixture keep their individual properties.

Parts of a mixture are not necessarily present in specific

ratios.

Compound

A compound has properties different than the elements that make it up.

The parts of a compound are present in specific ratio’s.

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 chemical compounds.

Heterogeneous Mixture

A mixture in which different materials can be easily distinguished.

Pizza, dry soup, chex mix, trail mix are all examples.

Solutions

Homogeneous mixture: is a substance in which two or more substances are uniformly spread out. For example salt water.

Solution is another term for homogeneous mixture.

Solutions

Solute is the substance being dissolved.

Solvent is the substance that dissolves a solute.

Solubility is the amount of a substance (solute) that will dissolve in a solvent.

Example

Salt water:

The water is the solvent

NaCl is the solute

Colloids and Suspensions

A colloid is a heterogeneous mixture that like a solution never settles. Milk and smoke are examples.

One way to tell a colloid from a solution is because milk is appears white because its particles scatter light. Called the Tyndall Effect.

Colloids

In a colloid the particles are mixed together but not dissolved.

The particles are relatively large and are kept permanently suspended.

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Colloids

A colloid will not separate upon standing.

The particles are constantly colliding, and this allows a colloid to scatter light – thus colloids often seem cloudy.

suspension

A suspension is a heterogeneous mixture containing a liquid in which visible particles settle.

River water

Kinetic theory of matter

The idea that all matter is made up of constantly moving tiny particles.

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