Matter and Change

Matter• Matter is anything that has mass and

takes up space. Stuff!

• There are three basic states of matter:– Solid (s) has definite shape and volume– Liquid (l) shape can change, still has definite

volume– Gas (g) no definite shape or volume– Draw a representation of the states of matter here.

Phase Changes• Matter can change from one state (or

“phase” to another)

• There are six possible phase changes. Energy is either absorbed or released.

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Deposition

Energy

• The universe consists of matter and energy. Energy does not have mass or take up space.

• Energy is involved when matter changes from one state to another.

• Solid + Energy Liquid “Melting”

Example:

Ice (s) + heat energy Water (l)

Energy Changes

• Endothermic- a process which requires, or absorbs energy. (Feels cold)– Ex: H2O (s) + energy H2O (l)

– Ex: Melting, evaporating, boiling

• Exothermic- a process which releases or gives off heat. (Feels hot)– Ex:

• Gasoline burns and releases heat• Ex: solidify, condensation

Classification of Matter

• There are two kinds of matter:– Pure Substances (elements and compounds)– Mixtures

• Elements- are pure substances– Can’t be broken down by ordinary means– Are found on the Periodic Table– Usually found as single atoms– Some gaseous elements exist as two atoms

bonded together (The HOFBrINCl gases)

Compounds• Compounds- are also pure substances

– Can be broken down by chemical reactions only– Are made up of two or more elements chemically

combined, or “bonded”– Always have a chemical formula that doesn’t change– The compound has new properties, not the same as

the original elements.

Examples of Pure Substances

• Elements:– Carbon– Oxygen– Gold– Neon– About 100 more!

(If you are not sure, check the periodic table.)

• Compounds:– Water, H2O– Sodium chloride, NaCl– Hydrogen peroxide, H2O2

– Methane, CH4

– Baking Soda NaHCO3

– Glucose C6H12O6

– There thousands and thousands of known compounds!

(If it has a chemical formula, it’s a compound.)

Mixtures• Mixture- a physical combination of two or more

substances.– A mixture can be separated by physical means– The components of the mixture retain (keep) their

original properties– The composition can vary (for example. A mixture

could be 50% A and 50% B, or it could be

only 30% A and 70% B.)

Examples of Mixtures

• Salt water ( H2O and NaCl)

• Sugar water ( H2O and C12H22O11)

• Air ( Nitrogen, Oxygen, and trace elements)

• Brass ( copper and zinc combine to form an alloy)

Mixtures

• There are two kinds of mixtures.– Homogeneous mixtures:

• Appear uniform, or the same, throughout• Also known as solutions

– Heterogeneous mixtures:• Not uniform in appearance or composition

Examples of Mixtures

• Homogeneous:– Air – Salt water– Sugar water– Brass– Solutions

• Heterogeneous:– Soil– Sand and water

mixture

– Sometimes you must look very closely, or even magnify.

Separation of Mixtures

• Mixtures can be separated by physical means. Physical means include:– Filtration separates components based on

their size– Distillation separates components based on

their different boiling points– Chromatography separates based on

differences in solubility

Filtration

Distillation

Chromatography

Physical and Chemical Changes

• Physical Change-– Is usually reversible (can be undone)– All phase changes are physical changes

• List the six phase changes here:– (s) (l) melting and (l) (s) freezing– (l) (g)–

– Dissolving is a physical change– Shape changes are physical changes (such

as: tearing, bending, etc.)

Physical and Chemical Changes

• Chemical Change-– Always produces a new substance– The new substance will have different

properties

• Evidence of Chemical Change– Color change– Bubbles of gas appear– A new solid forms (a “precipitate)– Temperature change

Chemical Changes

• Chemical Changes are also called chemical reactions.

• Chemical reactions always produce a new substance:– Rusting– Burning– Cooking– Digesting– There are many more!

Chemical Reactions

A + B Creactants yields products

Chemical reactions must obey the Law of Conservation of Mass:The mass of the products must equal the mass of the reactants.

In other words, matter is neither created nor destroyed

5 grams of A + 5 grams of B yields 10 grams of C

Properties

• A property is something you can observe or measure.

• There are two types of properties, physical and chemical.

Physical Properties• Physical properties can be measured or

observed without changing or destroying the sample

• Examples of physical properties– Mass– Color– Density– Melting and boiling points– Ductility and malleability (flexibility)

Physical Properties

• There are two types of physical properties– Extensive- these depend on the amount of the

substance. (Mass, length, and volume)

– Intensive- stay the same no matter what the amount of the substance is. (Color, density, conductivity, etc.)

Chemical Properties

• Chemical Properties- how a substance reacts with other substances– Reacts with water– Reacts with oxygen– Reacts with whatever– Even if it doesn’t react, that is also a chemcial

property– These are easy to recognize, always “React”

Chemical Properties

Corrosion

Flammability

Oxidizes