CHEMISTRY Cloth Strips bonding Atomic Structure drawings Balancing Equations Molar Solutions Acids and Bases Enzyme Lab Endothermic and exothermic reactions

Composition of Matter Matter - Everything in universe is composed of matter Matter is anything that 1. occupies space 2. has mass Mass – quantity of matter an object has Weight – pull of gravity on an object

Elements Pure substances that cannot be broken down chemically into simpler kinds of matter

96% of the mass of an organism is composed of 4 elements. (Coloring page) Carbon, Hydrogen Oxygen Nitrogen

Each element has a unique chemical symbol Consists of 1-2 letters First letter is always capitalized

The Nucleus Consists of positive charged protons and neutral neutrons Contains the mass of the atom

Atomic Mass Protons & neutrons are found in the nucleus of an atom Protons and neutrons each have a mass of 1 amu (atomic mass unit) The atomic mass of an atom is found by adding the number of protons & neutrons in an atom

The Electrons Negatively charged high energy particles with little or no mass Travel at very high speeds at various distances (energy levels) from the nucleus.

Stop to make sure we understand. Element C Atomic Number Protons Electrons Neutrons Mass Na

Outer energy levels have more energy than inner levels Each level holds only a certain number of electrons

Periodic Table Elements are arranged by their atomic number on the Periodic Table The horizontal rows are called Periods & tell the number of energy levels Vertical groups are called groups & tell the outermost number of electrons

Compounds Most elements do not exist by themselves Readily combine with other elements in a predictable fashion

8 is the perfect number If you are an atom that is. Every atom wants to have 8 on the outer shell. That is how compound “couples” form

A compound is a pure substance made up of atoms of two or more elements The proportion of atoms are always fixed. (Give and example)

Some molecules are large and complex

Why do atoms behave the way they do? Groups are read from the top and predict who each atom will react with by the number of electrons in their outer shell. Periods tell how big the atom is and how many electron shells there are.

Draw that atom!

You can read the Symbol box. You can read the periodic table. Now lets balance equations.

Energy and Chemical Reactions Living things undergo thousands of chemical reactions as part of the life process

Chemical Formulas Subscript after a symbol tell the number of atoms of each element H 2 0 Coefficients before a formula tell the number of molecules 3H 2 0

Atoms that gain electrons are called negative ions Because positive and negative electrical charges attract each other ionic bonds form

Chemical equations represent chemical reactions Reactants are shown on the left side of the equation Products are shown on the right side Reactant Product

The equation must be balanced! Bonds may be broken or made forming new compounds

Balancing Chemical Equations Worksheet

The Neutrons The number varies slightly among atoms of the same element Different number of neutrons produces isotopes of the same element

Radioactive isotopes Are used as tracers in the body.

Ra Radium From Uranium Radon detectors Radium City - youtube Clocks

Covalent and Ionic bonds

Solutions

Solutions A solution is a mixture in which 2 or more substances are uniformly distributed in another substance

Solute is the substance dissolved in the solution Particles may be ions, atoms, or molecules Solvent is the substance in which the solute is dissolved Water is the universal solvent

How to make a molar solution:

Dissociation of water Breaking apart of the water molecule into two ions of opposite charge OH - (hydroxide ion) H 3 O (hydronium ion)

Acids and Bases One of the most important aspects of a living system is the degree of acidity or alkalinity

Acids Number of hydronium ions in solutions is greater than the number of hydroxide ions HCl  H + + Cl -

Bases Number of hydroxide ions in solution is greater than the number of hydronium ions NaOH  Na + + OH -

pH Scale logarithmic scale for comparing the relative concentrations of hydronium ions and hydroxide ions in a solution ranges from 0 to 14  Each pH is 10X stronger than next  e.g. ph 1 is 10 times stronger than ph 2

the lower the pH the stronger the acid the higher the pH the stronger the base pH 7.0 is neutral

Buffers Control of pH is very important Most enzymes function only within a very narrow pH Control is accomplished with buffers made by the body Buffers keep a neutral pH (pH 7)

Buffers neutralize small amounts of either an acid or base added to a solution Complex buffering systems maintain the pH values of your body’s many fluids at normal and safe levels

Energy Transfer Much of the energy organisms need is provided by sugar (food) Undergoes a series of chemical reactions in which energy is released (cell respiration) The net release of free energy is called an exergonic (exothermic) reaction

Reactions that involve a net absorption of free energy are called endergonic (endothermic) reactions Photosynthesis is an example Most reactions in living organisms are endergonic; therefore living organisms require a constant source of energy

Most chemical reactions require energy to begin The amount of energy needed to start the reaction is called activation energy

Certain chemical substances (catalysts) reduce the amount of activation energy required Biological catalysts are called enzymes