Matter is anything that has mass and occupies space – Solid, Liquid, and Gas. Mass is the measure of the amount of matter present.
Substance, Element, and Compound
- Pure substance
- A substance made up of only one type of atom or molecule (no contamination) – constant properties and composition (the same chemical formula)
- Water (H2O), Salt (NaCl)
- A pure substance that cannot be broken down by ordinary chemical means (heating, add energy – electric current). A chemical formula for an element contains only 1 symbol. (O2, H2)
- Atom: The smallest discrete particle of an element.
- Chemical Compound
- A pure substance that can be broken down by ordinary chemical means.
- A chemical formula for a chemical compound contains 2 or more element symbols. (H2O)
- Molecule: The smallest discrete particle of a chemical compound. Atoms combine to form molecules.
2H2O (l) -> electric current -> 2H2 (g) + O2 (g)
- A random blending of 2 or more pure substances that do not react.
- Homogeneous – a mixture that is chemically and physically consistent
- Heterogeneous – a mixture that is no chemically and physically the same throughout
- Physical properties are based on observation or measurement with no change in the composition of matter.
- color, melting point
- Chemical properties are based on the reactivity of matter with a change in composition.
- chemical change
- iron rust: 2Fe (s) + O2 (g) + H2O (l) -> Fe2O3 (s) + H2 (g)
- Intensive properties do not depend on the amount of matter present.
- color, density, boiling point
- Chemical properties are always intensive properties.
- Extensive properties DO depend on the amount of matter present.
- mass, volume
- Law: Observations in nature to which there are no exceptions.
- Law of Mass Conservation
- In a chemical reaction, mass is neither created or destroyed.
- A Measurement is a quantitative observation that is represented with a number and a unit.