Elements, Compounds, Mixtures

Mixture

A combination of two or more substances that do not chemically combine. For example, cheese and tomato sauce do not react to form something new.

Magnetism

A magnet can be used to separate iron from aluminum.

Concentration

A measure of the amount of solute dissolved in a solvent.

Solution

A mixture that appears to be a single substance because systems are uniformly dispersed.

Compounds

A pure substance composed of two or more elements that are chemically combined. A compound has properties that differ from those of the elements that form it, and its own unique physical properties including melting point, density and color, and chemical properties: Reactivity, flammability.

Elements

A pure substance that cannot be separated into simpler substances by physical or chemical means. Elements can be grouped together by the properties they share. There are three major categories of elements.

Pure Substance

A substance in which there is only one type of particle

Suspensions

A suspension will temporarily mix when shaken (a snow globe, salad dressing, paints and some medicines) but will settle out and separate when left alone. Suspensions are items you need to "shake before using." They can be filtered, and do block or scatter light.

What is an example of breaking down a chemical compound?

Carbonic acid gives soda its fizz. When you open a soda, carbonic acid is broken down into carbon dioxide and water. These simpler compounds can then be broken down into the elements carbon, hydrogen and oxygen.

Breaking down a compound

Compounds can be broken down by chemical changes. The result of this process: 1. They are broken down into elements (pure substances). 2. They are broken down into simpler compounds, that can be broken down again.

formula for determining concentration

Concentration = grams of solute divided by millileters of solvent.

Separating the Substances in Mixtures

Distillation, magnetism, centrifugal force

Non-metals.

Do not conduct heat or electricity. Dull. Examples: Sulfur, iodine, neon.

Characteristic properties

Elements are identified by these characteristics, which can be physical or chemical. Elements may share properties.

Ratio of Elements in a compound

Elements join in a specific ratio (1 to 8, for water for example) This ratio is always the same. Compounds that have the same elements at different ratios are different compounds.

Chemical properties

Flammability, reactivity

States of solutions

Gas in liquid (soft drinks), liquid in liquid (antifreeze-alcohol in water), solid in liquid (saltwater, salt in water) solid in solid (brass-zinc in copper), gas in gas, (air, oxygen in nitrogen).

Types of solutions

Gas, solids, alloys (metals in metals)

Physical properties

Melting point, density, color, hardness, texture

Colloid

Milk, jello, mayonnaise are all colloids. A colloid has small particles floating throughout but they don't drop to the bottom. You can't filter these particles out, and they do scatter light. A colloid is like a clique: The particles all hang together.

How temperature changes solubility

Most solids are MORE soluble with heat, but gases become LESS soluble with warmth. A soda goes flat in the warm air; lemonade becomes easier to mix in heat.

Component ratio in a mixture

Ratios in a mixture, unlike ratios in a compound, are not specific. Granite is always feldspar, mica and quartz, for instance. It doesn't matter if there is more or less Feldspar.

Distillation

Separates mixtures based on the boiling point of the components, such as taking out salt from salt water.

Metals

Shiny, conduct energy and electric current. Examples: Lead, copper, tin.

Solubility

The ability of one substance to dissolve in another. In other words: How much sugar you can keep adding to hot water before the water can't hold any more of it and it will sink to the bottom.

Solvent

The substance in which the solute dissolves. Water is the solvent in salt water, for example. The substance that is present in the largest amount is the solvent.

Solute

The substance that dissolves in the solvent. Salt is the solute in salt water. There is less salt than water.

Metals, Non-Metals, Metalloids

These are the three major categories of elements.

Metalloids.

They have properties of both metals and non-metals. Also called semi-conductors.

Centrifuge

Through movement (often spinning) mixtures are separated by density (such as plasma from red blood)