States of Matter and Physical and Chemical Changes 1.

States of Matter and Physical and Chemical Changes

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Chemistry is the study of matter.

• What is matter?• Matter: anything that takes

up space (volume) and has a mass.

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Properties of matter:

• Physical properties: are observable and do not change the chemical composition of the matter. Examples of physical properties: different densities, melting points, boiling points, freezing points, colour, odour (smell) and state of matter (solid, liquid or gas).

• Chemical properties: are only observable through a chemical reaction, and do change the chemical composition of the matter (new substance produced by destroying the original substances). Ex: burning, rusting, reactivity with water or acid.

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• Chemical Properties: A good example of chemical properties is the way compounds or elements combine with each other during chemical reactions

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States of Matter

• Matter can be found in 3 states:

• 1. Solid

• 2. Liquid

• 3. Gas

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States of Matter• Solid: definite shape and

volume, molecules close together, rigid formation, little molecular movement (vibration). Particles in a solid are held together by very strong attractive forces (like strong magnets next to one another). There is an extremely small change in the volume of solids with changes in temperature and pressure.

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• Liquid: indefinite shape and definite volume, molecules further apart than solids, more molecular movement. Forces of attraction are a little weaker and allow particles to flow by one another (think of tipping a box of marbles – they will flow).

• Temperature and pressure changes have a small affect on the volume of liquids.

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• Gas: indefinite shape and volume.

• Molecules are far apart (no attractive forces between the particles because of the distance – think of magnets far away from one another.

• The most molecular movement (particles are in constant motion).

• Gas volumes are greatly affected by temperature and pressure changes.

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Kinds of Change:physical change: no new substance is

formed, properties such as size, shape, colour or state may change (example: Boiling water – have liquid water to start and water as a gas at the end or the heating element on a stove – black when off and red when on high and back t black when off again). Easily reversed.

chemical change: new substances (with new properties) are formed from 2 or more reacting substances. (example: rusting of iron or burning paper) Not easily reversed.

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Examples:

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Classify the following as a physical or chemical change:

• A) freezing water• B) burning gas• C) melting butter• D) stretching an elastic

band

• E) rusting a nail• F) tearing a piece of

paper• G) rotting an apple• H) water freezing

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Mixtures and Pure Substances:

• Matter can be broken down into two categories:

• 1. Pure substance: substances containing only one kind of matter (atoms or molecules). Examples: oxygen, water.

• 2. Mixtures: contains at least two kinds of matter that are physically mixed (blended) together (most things around us are mixtures). A mixture is a combination of pure substances. Ex: salt water, air, salt and pepper, dirt.

Classification of matter

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Glossary:• Pure substance: contains one type of

particle.– Elements: one kind of atom (Sulfur)– Compounds: contains at least two atoms of

different elements bonded together (H2O)

• Mixture: contains two or more types of particles intermingling, no chemical bonding.– Homogeneous: uniform throughout only see

one component (solution)– Heterogeneous: see the two components not

uniform (salt and pepper mixed)14

• Composed of two or more different atoms (elements)

• Examples:

water (H2O), 2 atoms of hydrogen, I atom of oxygen)salt (NaCl), 1 atom of sodium, 1 atom of chlorine

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• An element is a substance made up of only one kind of atom. (Iron is made up of iron atoms)

• The periodic table arranges elements according to their properties

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Heterogeneous

• 2 or more parts can be seen

• Different kinds of particles stay together.

• Mechanical (physical) mixing

• Ex: sand and salt, blood, milk

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Homogeneous

• Appears to be one substance

• Particles are intermingled• Are solutions (solute

substance dissolved) (Solvent substance that is doing the dissolving)

• Ex: air, salt water (salt is the solute and water is the solvent)

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Solution

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Classification of matter

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See two components (parts)

See one component (part)

Contains at least two elements (can be broken down into elements)

Only one kind of atom (can not be broken down)