Ms. Levasseur Biology
Atom: the actual basic unit - composed of protons, neutrons, and electrons Element: a substance that cannot be broken down into simpler substances pure
Molecule: a substance made of two or more atoms held together by chemical bonds can be of same type of atom Compound: a substance made of two or more DIFFERENT atoms
Just like cells are the basic unit of life, the ATOM is the basic unit of matter. They are very small. If placed side by side one million would stretch a distance of 1cm. The atom is made up of 3 particles. Particle Charge PROTON + NEUTRON NEUTRAL ELECTRON -
Electrons are not present within the atom, instead THEY REVOLVE AROUND THE NUCELUS OF THE ATOM & FORM THE ELECTRON CLOUD Helium atom NEUTRONS PROTONS ELECTRONS - + + - ATOMIC # = 2 (PROTONS) ATOMIC MASS = 4 (PROTONS & NEUTRONS)
Atoms of the same element that HAVE A DIFFERENT NUMBER OF NEUTRONS Some isotopes are radioactive. nucleus is unstable and will break down at a CONSTANT RATE over time. There are several practical uses for radioactive isotopes: 1. CARBON DATING 2. TRACERS 3. KILL BACTERIA / CANCER CELLS
a substance formed by the chemical combination of 2 or more elements in definite proportions Ex: water, salt, glucose, carbon dioxide
The cell is a COMPLEX CHEMICAL FACTORY containing some of the same elements found in the nonliving environment. carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) are present in the greatest percentages
Organic - Contain C, H, and O in some ratio (usually referred to as chemicals of life) Carbohydrates, Proteins, Lipids, Nucleic Acids Inorganic - usually "support" life - no specific ratio of C, H, and O Water (H 2 O), Carbon Dioxide (CO 2 )
Chemical bonds hold the atoms in a molecule together. There are 2 types of chemical bonds IONIC and COVALENT
Occur when 1 or more electrons are TRANSFERRED from one atom to another. When an atom loses an electron it is a POSITIVE charge. When an atom gains an electron it is a NEGATIVE charge These newly charged atoms are now called IONS Example: NaCl (SALT)
Occur when electrons are SHARED by atoms. These new structures that result from covalent bonds are called MOLECULES ** In general, the more chemical bonds a molecule has the more energy it contains SHARING IS CARING!
Water is not always pure. It is often found as part of a mixture. A mixture is a material composed of TWO OR MORE ELEMENTS OR COMPOUNDS THAT ARE PHYSICALLY MIXED Ex: salt & pepper mixed, sugar and sand can be easily separated
Two parts: SOLUTE SUBSTANCE THAT IS BEING DISSOLVED (SUGAR / SALT) SOLVENT - the substance in which the solute dissolves Materials that do not dissolve are known as SUSPENSIONS. Blood is the most common example of a suspension. Cells & other particles remain in suspension.
The chemical symbols and numbers that compose a compound ("recipe") Structural Formula Line drawings of the compound that shows the elements in proportion and how they are bonded Molecular Formula the ACTUAL formula for a compound C2H6O
Acids: always (almost) begin with "H" because of the excess of H+ ions (hydrogen) Facts about Acids Acids turn litmus paper RED and usually taste SOUR. You eat acids daily (coffee, vinegar, soda, spicy foods, etc )
Bases: almost always end with OHbecause of the excess of hydroxide ions (Oxygen & Hydrogen) Facts about Bases Bases turn litmus BLUE. Bases usually feel SLIPPERY to touch and taste BITTER.
measures degree of substance alkalinity or acidity Ranges from 0 to 14 0 5 strong acid 6-7 neutral 8-14 strong base
The goal of the body is to maintain HOMEOSTASIS (neutrality) to do this when ph is concerned, we add weak acids & bases to prevent sharp changes in ph. These are called BUFFERS
High surface tension High boiling point Density depends on the temperature
a process that changes one set of chemicals into another set of chemicals REACTANTS elements or compounds that you start with PRODUCTS elements or compounds that you end up with Chemical reactions always involve the breaking of bonds in reactants and the formation of new bonds in products