Chapter 1 NotesIntro to Matter 10/17/11
I) Describing Matter • Matter-anything that has mass and takes up space.
Properties of matter • 3 states of matter • Solid • Liquid • Gas
Characteristic properties – these are things that never change. • Ex. Diamonds
Boiling point • Point at which a liquid boils 1000C. • Melting point -Point at which solid melts 00 C.
Changes in Matter • Physical changes — changes the form of the substance not the identity. • Ex. Water melting, freezing, or steaming.
Chemical changes — substances that combine or break apart and form new substances. • Ex. Heating sugar into caramel
Types of Matter • Matter can be placed into two different categories. • Mixtures • Pure substances—elements and compounds.
Mixtures • Mixture—Two or more substances that are in the same place but not chemically combined. • Ex. Juice
Solution — the “best mixed” of all possible mixtures. • Ex. Sea water—salt and water. • Ex. Sugar water—sugar and water.
Pure Substances • Pure substance — made of only 1 kind of matter. • Ex. Sugar, salt, iron, aluminum, copper.
Elements • Elements — Cannot be broken down into other substances physically or chemically. There are more than 100 elements. You use about 30-40 of them everyday. • Ex. Nitrogen and oxygen.
Compounds • Compounds — A substance made of two or more elements that are chemically combined. • Ex. Water and Carbon dioxide.
Section 2 • What weighs more? A Kilo of bricks or a Kilo of feathers?
Weight vs. Mass • Weight—the measure of force of gravity on you. • An objects weight will change with gravity, but it’s mass does not.
Density • Density—relates mass and volume. Remember the kilo of bricks and kilo of feathers? • Density= mass/volume • D=m/v
Section 3—Particles of Matter • Atom – an atom is the smallest particle of an element.
Democritus • Democritus – Greek philosopher in 440 B.C.- he thought that you could chop matter into smaller and smaller pieces until you get to its smallest piece. He called this piece “atomos”, Greek for “uncuttable”.
Dalton’s Atomic Theory • John Dalton – 1802, British schoolteacher, Based on experiments he concluded: • Atoms can’t be broken into smaller pieces.
Dalton’s Atomic Theory 2. In any element, all the atoms are exactly alike. 3. Atoms of different elements are different. 4. Atoms of two or more elements can combine to form compounds.
Dalton’s Atomic Theory 5. Atoms of each element have a unique mass. 6. The masses of the elements in a compound are always in a constant ratio.
Molecules • Molecule – a group of atoms that are joined together and act as a single unit. • Chemical bond – the force that holds these two atoms together.
How small is small? • A sheet of paper is about 10,000 atoms thick. • There are 2,000,000,000,000,000,000,000 atoms of oxygen in a drop of water. H20. Twice that for Hydrogen.
How small is small? • Newspaper pictures are made of tiny dots of ink. Each dot contains a billion billion atoms! (That’s a 1 followed by 18 zeros).