Atoms and the Periodic TablePeriodic Table

Kinds of Matter Elements: Made of only one type of atom – if the substance isn’t in it’s very own box on the periodic table, it isn’t an element. Examples: Carbon Copper

Elements Some elements have a single letter as their symbol. Other elements have 2 or more letters for their symbol. Notice that only the first letter is capitalized.

Kinds of Matter Compounds Two or more elements chemically combined to form a new substance. Sodium (Na) is a metal that explodes in water. Chlorine (Cl) is a poisonous green gas. Together NaCl makes a new substance: table salt.

Kinds of Matter Mixture: Elements and/or compounds mixed together without being chemically combined. e.g. Chocolate chip cookies – the chips are not chemically combined with the cookie.

Structure of an Atom Nucleus Protons: + charge Neutrons: no charge (neutral) Electron Cloud Electrons: - charge Orbit the nucleus Very little mass

Structure of an Atom Atomic Number Number of protons All atoms of an element contain the same number of protons. e.g. all silver atoms have 47 protons. Atoms have the same number of electrons as they have protons (atoms are neutral) 47 Ag

Role of Electrons Form bonds between atoms In carbon dioxide (CO 2 ) the oxygen atoms (O) stick to the carbon atom (C) because all 3 atoms share electrons to make a bond.

Physical Change A change from one phase of matter into another. (e.g. solid melting into a liquid) A change into a different shape or texture, but not a change into a new substance. (e.g. cutting or bending a substance) Dissolving Amount of matter (# of grams) does NOT change.

Chemical Changes A reaction that produces a new substance. The mass of the reactants (the things you add together) is the same as the mass of the products (the substances produced by the reaction) Nope, this one just releases CO 2 gas Nope, this one just releases CO 2 gas Now, this would be fun.