Chapter Two: Matter

Chapter Two: MatterMatterAtom-basic unit of matter 1. Subatomic particles- protons, neutrons, electrons A. Protons- positive charge, center of atom (nucleus)B. Neutron- neutral, center of atom C. Electrons- negative charge, in constant motion around nucleus

MatterElements- pure substance that consists entirely of one type of atom 1. Represented by symbol2. Atomic number- number of protons in an atom Number of protons = number of electrons 3. Atomic mass- protons and neutrons A. Number of neutrons = atomic mass atomic number

Matter 4. Electron Cloud- area around nucleus where electrons are orbiting 1st level- holds 2 electrons 2nd level- holds 8 electrons 3rd level- holds 8 electrons 4th level- holds 18 electrons Example 17 atomic number Cl symbol 35.453 mass number

Atomic number: Atomic mass:Number of protons:Number of neutrons:Number of electrons: Isotopes- atoms that have an equal number of protons but different number of neutrons Radioactive isotopes- nuclei are unstable and break down at a constant rate over time Geologists determine age of rocks and fossils by analyzing the isotopes in them Radiation from some isotopes are used to treat cancer Used as tracers

Compounds- substance formed by the chemical combination of two or more elements in definite proportions Example H2O

Chemical Bonds Valence electrons- electrons that are available to form bonds Ionic bonds- when one or more electrons are transferred from one atom to another Example- NaCl

Covalent bond- forms when electrons are shared between atoms Example- H2O

Ions- positive or negative charged atomPositive charge= lose an electronNegative charge = gain an electron

Molecules- the smallest unit of most compounds, the structure that results when atoms are joined together by covalent bonds Subscript- number of atoms Coefficient- number of molecules of a compound element number of atoms H2O2H2O2

Van der Waals Foreces- when molecules are close together, a slight attraction can develop between the oppositely charged regions of nearby molecules Example: Geckos

Physical Changes: change in form of substance not the chemical makeup Ex: size, shape, states of matter

Chemical changes- a substance changes into a new substance Example: rusting, digesting, rotting

Properties of WaterMost abundant compound in living thingsCovers s of Earths surfaceExpands when it freezes so ice is less dense than liquid water

Water molecule- neutral 1. polarity- an uneven sharing of electrons between the O and H atoms Example: DRAW A WATER MOLECULE

3. Hydrogen bondsWater can have as many as four H bonds at the same time A. cohesion- attraction between molecules of same substance Surface tension- the force that occurs because of cohesion Example- insect walk on water, drops of water form beads on smooth surface

B. adhesion- attraction between molecules of different substances Example- meniscus- the adhesion between water molecules and graduated cylinder are stronger than the cohesion between water molecules 1. Capillary action- adhesion causes H20 to rise in a narrow tube A. Example- draw H20 out of roots of plant and up into the stem and leaf

B. Solutions and Suspensions 1. Mixture- a material composed of two or more elements or compounds that are physically mixed together but not chemically combined Example- salt and pepper, sugar water A. Solution-mixture of two or more substances in which the molecules of the substances are evenly distributed 1. Example- Salt water Solute- the substance that is dissolved (salt)Solvent- the substance in which the solute is dissolved (water)H2O- the greatest solvent of Earth B. Suspensions- mixture of water and undissolved materials

C. Acids, Bases, pH1. pH scale- indicates the concentration of H ions in solution A. 0-14pH 7 = neutral, concentration of H ions and OH ions are equal Example- pure water pH below 7= acidic, more H ions than OH ions pH above 7= basic, more OH ions than H ions

BasicC. Acids, Bases, pH2. Acids- a compound that forms H ions in solution pH of 1-3 = strong acid Example- HCl

3. Bases- compound that produces hydroxide (OH) pH of 11-14 = strong base Example- lye , NaOHIII. Carbon CompoundsOrganic Chemistry- study of all compounds that contain bonds between carbon atoms A. Chemistry of carbon1. carbon atoms can bond to other carbon atoms to form very long chains B. Macromolecules- very large molecules1. monomers- smaller unit that can join together with other small units to form polymers 2. polymers- large compound formed from combinations of many monomers

3. Dehydration synthesisThe formation of a chemical bond by removing a water molecule

4 types of macromolecules: CarbohydratesLipidsNucleic acids Protein

Carbohydrates:compounds made up of C, H, O atoms in a 1:2:1 ratio A. living things use carbohydrates as their main source of energyB. living things store extra sugar as starch (long chains of sugar molecules ) C. monosaccharides- single sugar molecules Ex: glucose, galactose (milk), fructose (fruit)Disaccharides- sugars made up of two covalently bonded monosaccharides Ex: sucrose (table sugar), lactose (milk sugar) D. polysaccharides- large macromolecules formed from monosaccharides Example: glycogen (animal starch), causes muscle contractions Example: cellulose- tough fibers that give plants much of their strength and rigidity. Major component of wood and paper 2. Lipids Macromolecules made mostly of carbon and hydrogen atoms and are not soluable in H2O A. stores energy, waterproof coverings, steroids B. example- fats, oils, waxes 2 types: 1. saturated- solid at room temp Example: butter 2. unsaturated- liquid at room temp Example: olive oil

3. Nucleic Acids Macromolecules that contain H, O, N, C, and P which are formed from Nucleotides (Page 47)A. nucleotide (monomer)- consists of sugar, phosphate, nitrogen base B. Store and transmit genetic infoC. 2 kinds- DNA deoxyribose nucleic acid sugar = deoxyriboseRNA- ribonucleic acid sugar = ribose

4. Protein Polymers of amino acids which are made of N, C, H, O. They control rate of reactions, build bones and muscles A. 20 different amino acids B. instructions for arranging amino acids into different proteins which are stored in DNAC. each protein has a specific role D. have an amino group (-NH2) on one end, a carboxyl group (-COOH) on the other end and an R group. The R group makes proteins different.

IV. Chemical Reactions and EnzymesA. Chemical reactions- process that changes one set of chemicals into another Example: Iron (Fe) + O rust H+ O H2O

Reactants- what you start with Products- whats produced

SubscriptB. Energy Changes 1. Chemical reactions release energy- exothermic A. occur spontaneously B. energy released in form of heat 2. Chemical reactions that absorb energy- Endothermic A. will not occur without a source of energy B. in plants, the energy comes from sun in animals, the energy comes from food

Activation Energy and Catalysts C. Activation Energy -the energy needed to get a reaction startedD. Catalysts- substance that speeds up the rate of a chemical reaction 1. Catalysts lower a reactions activation energy Enzymes- proteins that act as biological catalysts to speed up chemical reactions in cells A. substrate- reactant of an enzyme- catalyzed reactionB. Substrates bind to a site on the enzyme called the active site C. Enzyme-Substrate Complex- the enzyme and substrate comes together to form this D. Lock and Key model- the fit of the enzyme and the substrate is so precise that the fit is often referred to as this

26