Chemistry of Life

Matter Anything that has mass and takes up space. 3 types of matter: a). Solid b). Liquid c). Gas

Solids Any substance that has a definite shape and definite volume.

LIQUID Any substance that has a definite volume but not a definite shape. It takes the shape of its container.

Gas Any substance that has no definite shape or definite volume.

Physical Change Changing the physical properties of a substance without changing the substance itself.

Physical Properties The characteristics of a substance that you can observe with the senses. They include: shape color volume texture odor

ATOMS The smallest particle of matter that can exist and still have the properties of a particular kind of matter.

1. Nucleus – central part of the atom Atoms are composed of: 1. Nucleus – central part of the atom 2. Protons – positively charged particles (+) 3. Neutrons – uncharged particles 4. Electrons – negatively charged particles (-) electrons protons neutrons orbit

Orbits (Energy Levels) A region around the nucleus in specific energy levels. There are 7 energy levels known to date. 1st energy level holds a maximum of 2 electrons. 2nd energy level holds a maximum of 8 electrons. 3rd energy level holds a maximum of 18 electrons.

Elements http://www.chemsoc.org/viselements/pages/page3.html Substances that are made up entirely of atoms of the same kind and cannot be divided into simpler substances by ordinary chemical means.

Symbol – a shorthand method of representing an element. Atomic Number - # of protons in the nucleus of the element. Atomic Mass Number - # protons + # of neutrons # protons = # of electrons; atoms are electrically neutral

How many protons, electrons, and neutrons are found in the following atoms? Calcium – protons – electrons – neutrons - Iodine – protons – electrons – neutrons - I 53 74 Ca 20 Gold – protons – electrons – neutrons - Au 79 118

Molecule – the smallest part of a substance that has all the chemical properties of that substance. Made up of atoms of the same or different kinds of atoms. Compound – matter made up of 2 or more atoms that are chemically combined from different elements. H2O NH3 O2 2NaCl 4H2 CO2 He

Chemical (Molecular) Formulas Shows the kind and number of atoms in a molecule or compound. Ex: H2 - hydrogen gas H – symbol 2 – subscript 2 atoms of Hydrogen 2H2O C6H12O6

Chemical Change Always uses or gives off energy Results in a new substance Ex: H2 + O2  2H2O Na + Cl  NaCl

Mixtures – substances that are combined but not changed chemically Mixtures – substances that are combined but not changed chemically. Ex: cereal & milk vegetable salad How could a mixture of salt and water be separated? 2 types: a) homogeneous – one in which the substances are evenly distributed. b) heterogeneous – the substances are not evenly distributed.

Mixtures Solution – a mixture that is formed when the molecules of one substance mix evenly with those of another substance. ex: Kool-Aid lemonade Suspension – a heterogeneous mixture containing particles distributed with a liquid, gas, or solid. ex: soil & water RBC & blood Colloid – a mixture composed of particles dispersed in a medium ex: gelatin (partly solid & partly liquid) How is fog a colloid?

Acids & Bases Acid – a chemical that produces hydrogen ions in a water solution. Ex: HCl H2SO4 Base – a chemical that produces hydroxide ions in a water solution. Ex: NaOH

pH pH scale – scale for measuring how acidic or basic various solutions are. Ranges from 0 to 14 a solution w/a pH of 7 is neutral a solution w/a pH below 7 (0 to 6.9) is acidic a solution w/a pH above 7 (7.1 to 14) is basic Ex: stomach acid vinegar milk blood soap 1 3 6.5 7.3 10