Chapter 2: Chemistry Matter: Anything that has mass and volume Mass – amount of matter Volume – how much space it occupies Weight?  pull of gravity Characteristics: Physical Properties – mass, volume, color, odor, shape, texture, taste, hardness, melting point, boiling point, phase (solid, liquid, gas) Chemical Properties – describe a substances ability to change into a new substance as a result of a chemical change

Chemical Changes

Physical Reaction / Chemical Reaction? Chapter 2: Chemistry Physical Reaction / Chemical Reaction?

Physical vs. Chemical Changes Aluminum foil is cut in half Milk goes sour Gasoline is ignited Clay is molded into a new shape Butter melts on warm toast You take an antacid to settle your stomach Water evaporates from the surface of the ocean Rust forms on a nail left outside A juice box in the freezer freezes Rubbing alcohol evaporates on your hand Physical Chemical Chemical Physical Physical Chemical Physical Chemical Physical Physical

Chapter 2: Chemistry Atoms – smallest unit of matter Protons – positively charged particles Neutrons – no charge Electrons – negatively charged particles Atomic number - # of protons Atomic mass - # of protons + neutrons

Chapter 2: Chemistry Chemical Elements: Isotopes Radioactive Isotopes Made up of 1 type of atom Isotopes Have same #’s of protons and electrons, but differ in # of neutrons Radioactive Isotopes Can be good or bad Age of fossils – C14 Medically – diagnose & treat Radiation given off can damage molecules/DNA

Chapter 2: Chemistry Compounds and molecules: Made up of 2 or more elements Ionic and covalent bonding Ionic - Give and take of electrons ( Na Cl ) Covalent – Sharing of electrons

Chapter 2: Chemistry Chemical Reactions Structural Formulas Anytime a chemical bond is formed or broken a reaction occurs: Reactant + Reactant = Product Na + Cl = NaCl Structural Formulas Shows arrangement of elements in a compound

C H O N Chapter 2: Chemistry 6 12 1 8 16 7 14 Elements that make up the human body C 6 12 H 1 O 8 16 N 7 14 Protons (P + N) 6P 6N 8P 8N 7P 7N 1P 0N

Chapter 2: Chemistry Colored Pencils: Color elements at top of page, then color amount of that element found in a shrub and a rabbit Hydrogen: White Oxygen: Blue *Carbon: Black Nitrogen: Red Phosphorus: Green Calcium: Purple

Isotope – different # of P & N Ion – a charged particle P ≠ E Same! Element Atomic Number (# of P) Mass Number (P+N) Number of Protons (+) Number of Neutrons (mass # - protons) Number of Electrons (-) Ion, or Neutral Atom Aluminum (Al) 13 27 Neutral atom Bromine (Br) 35 45 36 Carbon (C) 6 14 13 14 35 80 Ion (-) 12 6 Neutral atom Isotope – different # of P & N Ion – a charged particle P ≠ E Neutral Atom – P = E

Isotopes, Ion, or Neutral Atom Same! Element Atomic Number (# of P) Mass Number (P+N) Number of Protons (+) Number of Neutrons (mass # - protons) Number of Electrons (-) Isotopes, Ion, or Neutral Atom Helium (He) 2 4 Neutral atom Hydrogen (H) 1 Lithium (Li) 3 7 Isotope – different # of P & N Ion – a charged particle P ≠ E Neutral Atom – P = E

Isotopes, Ion, or Neutral Atom Same! Element Atomic Number (# of P) Mass Number (P+N) Number of Protons (+) Number of Neutrons (mass # - protons) Number of Electrons (-) Isotopes, Ion, or Neutral Atom Nitrogen (N) 14 Neutral Atom Oxygen (O) 18 8 16 6 Potassium (K) 39 19 Isotope – different # of P & N Ion – a charged particle P ≠ E Neutral Atom – P = E

Chapter 2: Chemistry - Water  H2O Polarity + The oxygen side of the molecule is negative and the Hydrogen side is positive With 8 Protons in its nucleus, an oxygen atom has a much stronger attraction for electrons than does the hydrogen atom with a single proton in its nucleus. H O + -

Chapter 2: Chemistry A water molecule is polar because there is an uneven distribution of electrons between the oxygen and hydrogen atoms. Because of their partial positive and negative charges, polar molecules such as water can attract each other

Strong attraction between water molecules produces surface tension Chapter 2: Chemistry Cohesion – an attraction between molecules of the same substance. Strong attraction between water molecules produces surface tension

Chapter 2: Chemistry Cohesion at work!

Chapter 2: Chemistry Adhesion – an attraction between molecules of different substances.

Chapter 2: Chemistry Water is often found as a mixture Mixture – material composed of two or more elements or compounds that are physically mixed together, but not chemically combined. Two types of mixtures that can be made with water: Solutions Suspensions

Chapter 2: Chemistry Solution: Mixture of two or more substances in which the molecules of the substances are evenly distributed. Solute – Dissolved matter in a solution (thing being dissolved) Solvent – does the dissolving ***Water is the universal solvent

Chapter 2: Chemistry Suspensions A mixture of water and non-dissolved materials

Chapter 2: Chemistry + H+ H2O + OH- Acids, Bases and pH water Hydrogen ion Hydroxide ion water +

Chapter 2: Chemistry Acids Any compound that forms H+ ions in solution Higher concentrations of H+ ions than water Have pH values below 7 Bases Any compound that forms OH- ions in solution Lower concentrations of H+ ions than water Have pH values above 7

Chapter 2: Chemistry pH Scale:

Chapter 2: Chemistry Buffers: Chemical substances made by the body to regulate pH