“atomos” Greek meaning unable to cut

Subatomic Particles Democritus thought matter had a limit to how far it could be cut. He used the term “ atom” to describe this smallest particle. Protons (in nucleus, positive charge, atomic number) Neutrons (in nucleus, no charge, mass only) Electrons ( orbit nucleus, negative charge, little mass, move fast)

Elements & Isotopes Element: pure substance, all one type of atom Elements Listed on the Periodic Table (Names & Symbols Isotopes: alternative forms of an element, that vary by neutron number, have the same chemical properties Radioactive isotopes: those having unstable nuclei that can break down at a constant rate over time

Compounds 2 or more elements chemically c0mbined in specific proportions (H2O) Physical and chemical properties of the elements making up a compound are usually different from what they are when they are alone. (Na & Cl combine to make NaCl. ) Not a good idea to use Na and Cl separately.

Chemical Bonds-Ionic Ionic bonds: forms when one or more electrons is transferred from one atom to another, creating oppositely charged ions in the process. Oppositely charged ions attract each other, forming an Ionic Bond (+ attracts -) Gain electrons=negatively charged ion Lose electrons= positively charged ion

Chemical Bonds-Covalent Covalent bond forms when atoms share electrons, forming a “molecule” Molecule: the smallest unit of most compounds H2O is an example of a covalent bond Covalent compounds ( those containing covalent bonds)

Van der Waals Forces A slight attraction that develops between the oppositely charged regions of nearby molecules These forces help creatures like the gecko grip smooth, vertical surfaces

H 2 O (the universal solvent) Water is electrically neutral (8 protons, 8 electrons) but is a polar molecule One side of the water molecule has a higher probability of the electrons being closer than the other side. (nearer the Oxygen side) Water is a “bent” molecule. That is to say, water is polar. It has an uneven distribution of electrons between the hydrogen and oxygen atoms.

Hydrogen bonds The polarity of H2O molecules allows for a somewhat weak attraction between water molecules. This is a “hydrogen bond” Cohesion: an attraction between molecules of the same substance. (water attracted to water) Adhesion: an attraction between molecules of different substances. (Capillary action) Capillary action is what draws water up into a narrow tube against the force of gravity. This is how plants (tall trees) get water up to their highest regions

Solutions and Suspensions Mixtures: 2 or more elements or compounds physically mixed together but not chemically combined. Solution: in a salt/water solution, the salt is the solute and the water is the solvent Suspensions: material suspended, but not dissolved in a liquid Some body fluids are solutions and some are suspensions. (blood is both)

Acids,Bases, and pH pH scale H2O = H+ + OH-

pH Scale pH runs from 1-14 Neutral is 7, 7 is base Base=alkaline Buffers are weak acids or bases that can react with strong acids or bases to prevent sharp, sudden pH changes

Carbon Compounds Organic chemistry: carbon based chemistry Macromolecules: giant molecules Monomers (small) join together to form polymers (large) Organic compounds found in living things include carbohydrates, lipids(fats), nucleic acids, and proteins

Organic compounds Every carbon atom must make 4 bonds This is methane

Ethene 4 bonds around each C C bonded to C with a double bond This is ethene

Acetylene Unsaturated (not the maximum number of H bonds) Each C has 4 bonds

Carbohydrates Contain C, H, and O in a 1:2:1 ratio Provide the main source of energy for living things Carbohydrates provide some material for structural development in plants monosaccharides : single sugar molecules Polysaccharides: carbohydrates macromolecules ( glycogen)

Lipids Mostly C & H Includes fats, oils, and waxes Energy storage Important is some biological membranes and waterproof coverings Saturated: contains the maximum possible number of hydrogen atoms Polyunsaturated: contains at least one carbon- carbon double bond

Nucleic acids Macromolecules containing H, O,N, C and P Polymers assembled from individual nucleotides A nucleotide consists of a 5-carbon sugar, a phosphate group, and a nitrogenous base Nucleic acids store and transmit genetic information 2 types of nucleic acids. Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA)

Proteins Proteins are macromolecules that contain N along with C, H, & O Proteins are polymers of molecules called amino acids Amino acids are compounds with an amino group (-NH2) on one end and a carboxyl group (–COOH) on the other end Each amino acid is different from the other by a side chain called an R-group

Amino acid structure

Alanine and Serine (2 amino acids)

What proteins do. Some proteins control the rate of reactions and regulate cell processes Some proteins are used to form bones and muscles Some proteins transport substances in and out of cells or help fight disease

Proteins have up to 4 levels of organization. First level is the sequence of amino acids in a protein chain Second, the amino acids within a chain can be twisted or folded Third, the chain itself may be folded Proteins with more than one chain may have a specific spatial arrangement

Chemical Reactions and Enzymes Chemical reaction-a process that changes one set of chemicals into another set of chemicals Some chemical reactions are slow (oxidation/rust) some are fast (oxidation of hydrogen) Reactants-the elements or compounds that enter the reaction Chemical reactions always involve the breaking and making of chemical bonds and thus new products Energy is involved (exothermic or endothermic)

An exothermic chemical reaction

Energy in reactions Exothermic reactions often occur spontaneously or need some “activation energy) ie. Kick start but once they get started, energy is released. Endothermic reactions absorb energy. Example of absorbing energy is using electricity to break the bonds of H2O to get the components of H2O

Activation Energy Even exothermic reactions may need a “spark” to get started. Activation energy is the energy needed to get a reaction started. The match to light the firecracker would provide the activation energy.

Enzymes Catalyst-a substance that speeds up the rate of a chemical reaction. This works when the catalyst lowers the activation energy needed. Enzymes are biological catalysts Enzymes provide a site where reactants in cells can be brought together to react. The reactants of enzyme-catalyzed reactions are known as substrates.