Types of Matter

Pure substance

a material that has a uniform and definite composition (chemically)

two kinds

1. element

2. compound

element

1 type of atom

(O₂) = Oxygen

compound

2+ elements chemically combined

NaCl

mixture

1. homogenous

2. heterogenous

homogenous

uniform

*solution

heterogenous

not uniform

solutions are…

not always liquid

allotropes

different forms of a given element

chemical changes

chemical properties related to ability to chemically combine

diatomic elements

A diatomic element is a molecule composed of two atoms of the same or different chemical elements. The seven diatomic elements that exist in nature are:

1. Hydrogen (H₂)

2. Nitrogen (N₂)

3. Oxygen (O₂)

4. Fluorine (F₂)

5. Neon (Ne₂)

6. Iodine (I₂)

7. Chlorine (Cl₂)

These elements typically form diatomic molecules to achieve stability.

solution

solute + solvent

all elements are found on the…

periodic table of elements

H₂O is…

a universal solvent

observations of a chemical change

1. formation of a gas (bubbles)

2. color change

3. exchange of heat energy (endothermic/exothermic)

4. production of light

5. precipitate formation

extensive physical properties

dependent upon the amt. of substance

• length

• volume

• anything measurable

intensive physical properties

independent upon the amt. of substance

• density

heterogenous mixtures have two categories…

suspension/colloid

suspension

able to settle down; substance/mixture with large particles

colloid

non-transparent, uniform, large particles

Tyndall effect

ability to scatter light

filtration

heterogenous mixtures composed of solids and liquids

• sand and water

centrifugation

heterogenous mixtures composed of solids and liquids

• blood

distillation

homogenous mixtures; based on differences in boiling points

crystallization

separation technique resulting in the formation of pure solid particles of a substance

decantation

separation of mixtures of immiscible liquids/liquid + solid mixture (suspension)

chromatography

separates components of a mixture (mobile phase) on basis of tendency of each to travel/be drawn across the surface of another material (stationary phase)

*separation occurs because various components of ink spread through paper at different rates

law of conservation of mass

states that mass is neither created nor destroyed during a chemical reaction—it is conserved

Mass_reactants = Mass_products

law of definite proportions

• an important characteristic of compounds is that the elements comprising them combine in definite proportions by mass

• this law states that regardless of the amount, a compound is always composed of the same elements in the same proportion by mass

• the mass of the compound is equal to the sum of the masses of the elements that make up the compound

• the ratio of the mass of each element to the total mass of the compound is a percentage called the percent by mass

percent by mass (%) = mass of element/mass of compound x 100

law of multiple proportions

• ratios express the relationship of elements in a compound

• the two distinct compounds, water (H₂O) and hydrogen peroxide (H₂O₂) illustrate this law

• each compound contains the same elements (hydrogen and oxygen)

• water is composed of two parts hydrogen (the element that is present in different amounts in both compounds)