Properties and Change 8.P.1 Matter Properties and Change 8.P.1

Atom Def. Basic unit of a chemical element. Protons; a subatomic particle that has a positive charge. Neutrons; a subatomic particle with no charge (neutral). Electrons; a subatomic particle that has a negative charge. Valence electron; electrons on the outer valence shell. It’s important because; they determine which atoms they are most likely to combine with.  

Atomic Theory Atomic Number; the number that tells the number of protons in the nucleus of an atom. Write 10 element symbols with their atomic #. Atomic Mass; the total number of protons and neutrons in the nucleus. Atomic Mass Number; the average mass of that element and its isotopes.

Atomic models 12 11 Mg Na Magnesium Sodium 24.31 22.99 Figure out how many protons, electrons and neutrons are in these atoms

Bohr Models Draw Bohr models of three elements and give the valence number of each. Here is an example of Helium, valence of 2 electrons.

Periodic Table of Elements Dmitri Mendeleev created the PTE The periodic table is set up from most reactive to less reactive. Grouped by metals, metalloids, nonmetals. Increasing atomic # from left to right.

Two elements that have similar chemical properties… The most reactive group of metals is ____________the second most reactive is _______________ The most reactive group of nonmetals is ____________ The least reactive elements are at the bottom of the group. The _____________ will not react with other elements. Periods As you go from left to right the number of protons and electrons increase, the valence level is the same.

Properties of Metals, Non-metals and Metalloids.

Chemical and Physical Properties and Changes.

Pure substance vs. mixture

Chemical Reactions Reactant; the materials present at the beginning of a reaction. Photosynthesis 6H2O + 6CO2 + light energy → C6H12O6 + 6O2 Product; substance that results from the reactants. Respiration C6H12O6 + 6O2 → chemical energy + 6H2O + 6CO2 Law of Conservation of Matter Matter can neither be created nor destroyed. It can, however be changed.  2H2 +O2 → 2H2O H=4 O=2 → H=4 O=2

Evidence of Chemical Reactions Description Example 1. Color change   Mixing Kool-Aid in water Fire works 2. Temperature change Increase or decrease in temp. Yeast in vinegar Baking soda/vinegar 3. Gas formation Formation of bubbles (CO2) 4. Percipitate A solid forms in a liquid. Silver nitrate in alcohol