CH. 3 Matter & Atomic Structure Element – a substance that can’t be broken down into simpler substances. –Ex. Au, Cu, O, C, N, H, Na, Cl, F, Ca, Mg, Sn, Pb, etc. Atom – the smallest part of an element. 1. protons = + charge, in nucleus 2. neutrons = no charge, in nucleus 3. electrons = - charge, in electron clouds.

Atomic # = # of protons in the nucleus. Mass # = total number of protons and neutrons in the nucleus. Mass # - Atomic # = # of neutrons. Energy Levels = the area outside the nucleus where electrons are found. –1 st = 2, 2 nd = 8, 3 rd = 18, 4 th = 32, etc. Isotopes = atoms of the same element with different mass numbers. The neutrons differ from one atom to the next.

Compound – a substance that is composed of atoms of 2 or more different elements that are chemically combined. Chemical Bond – forces that hold the elements together in a compound. –1. Ionic Bond – a forced attraction between oppositely charged elements. Electrons are gained or lost due to this bond. –Ex. NaCl, LiF, HCl, etc. The net electrostatic charge is zero when elements form an ionic bond.

–2. Covalent Bonds – This bond is created when atoms share electrons between them. The atoms that form a covalent bond usually have the same charge. –Ex. H2O, CH4, H2, N2, Cl2, etc. Ions – an atom that gains or loses electrons. These are charged particles. Mixtures – a combination of 2 or more substances. –1. Heterogenous Mixture =One can distinguish the substances that make up the mixture. Ex. Toss Salad, Pizza, Mixed vegetables, etc. –2. Homogenous Mixture = One can’t distinguish the substances that make up the mixture. Ex. Pop, Kool-aid, Tomato soup, etc.

Acids – a solution that contains hydrogen ions (H+) in water. –Corrosive, electrolytes, sour taste, pH lower than 7. –Ex. HCl, HF, H2SO4, HNO3, etc. Bases – a solution that contains hydroxide ions (OH-) in water. –Corrosive, electrolytes, bitter, pH higher than 7. –Ex. NaOH, LiOH, NH4, etc. A pH of 7 is neutral.

States of Matter 1. Solid – the atoms are arranged in a crystalline structure. They have definite shape and volume 2. Liquid – the atoms in a liquid move faster than a solid. They have no shape, but they have volume. 3. Gas – the atoms move the faster yet in a gas. They have no shape or volume. 4. Plasma – the matter is heated to temperatures greater than 5000° C. –Ex. Lightning, neon sign, stars.

Evaporation – from liquid to a gas. Condensation – from gas to a liquid. Sublimation – from a solid to a gas. Conservation of matter and energy = matter & energy can neither be created nor destroyed, it can only be converted from one form to another.