Presentation on theme: "The Chemistry of Life. Section 2.1 Atoms The basic unit of matter are atoms. 100 million atoms would make a row only about 1 cm long! Consists of subatomic."— Presentation transcript:
Subatomic particles Protons- positively charged. Neutron- has no charge. - They form the nucleus of the atom. Electrons- negatively charged with 1/1840 the mass of a proton. - In constant motion in space around the nucleus.
Elements A chemical element is a pure substance that consists entirely of one type of atom. Can you name some? The number of protons in an atom of an element is the element’s atomic number. - Carbon: atomic number 6 - Has 6 protons and 6 electrons
Isotopes Atoms of the same element that differ in amount of neutrons. - Sum of protons and neutrons in nucleus is the mass number.
Chemical Compounds A substance formed by the chemical combination of two or more elements. - Water: H 2 O, 2 molecules of hydrogen 1 molecule of oxygen
Chemical Bonds An ionic bond is formed when one or more electrons are transferred from one atom to another. - An atom that loses electrons = positive - An atom that gains electrons = negative Example: Table Salt, NaCl
Chemical Bonds A covalent bond forms when electrons are shared between atoms. - Example: Water, H 2 O
2.2-Water A water molecule, H 2 O, is neutral. It is polar. Water molecules are held together by hydrogen bonds.
Hydrogen bonds Cohesion is an attraction between molecules of the same substance. Adhesion is an attraction between molecules of different substances.
Solutions and Suspensions A solution is an even mix of components. - A solute is the substance that is dissolved (salt) - A solvent is the substance in which the solute dissolves (water) A suspension is a mixture of water and non-dissolved material Example- blood
pH scale Ranges from 0-14. Solutions with a pH below 7 are acidic. Solutions with a pH above 7 are basic.
2.4-Chemical Reactions A process that changes one set of chemical reactions. - Reactants: elements that enter into a reaction. - Products: elements that are produced by a chemical reaction. H 2 + O H 2 O
Activation energy The energy to get a reaction started. It is a factor in whether the overall chemical reaction releases energy or absorbs energy.
Enzymes A catalyst is a substance that speeds up the rate of a chemical reaction. Enzymes are proteins that act as biological catalysts; speed up reactions in cells.