Composition of Matter Section 1

Matter and Mass Matter - anything that occupies space and has mass Mass – quantity of matter an object has – Mass is not the same as weight

Matter 1. Substance – can write chemical formulas 2. Mixtures – made of different substances in variable ratios – Homogeneous – solutions – Heterogeneous – mixture of physically distinct substances with different properties

Elements Elements – substances that cannot be broken down chemically into simpler kinds of matter Most common elements in living things: – O – C – H – N

Atoms Atom – simplest part of an element that retains all the properties of that element Mainly empty space Contain nucleus and outer energy levels Net charge = 0

Parts of an atom Nucleus – Protons (+) – Neutrons (neutral) # protons=# electrons (except if its an ion) Orbital's – Electrons (-)

Electrons and Orbital’s High energy & little mass Orbital’s – 3D region around a nucleus that indicates probable location of electron – Orbital’s further away have greater energy 1 st – 2 e- 2 nd – 8 e- 3 rd – 18 e- 4 th – 32 e-

Specifics Atomic number= number of protons Mass number = protons + neutrons Chemical symbol = name of element

Isotopes Isotope- atoms of same element that have different number of neutrons Since the number of neutrons is changing, what else will change?

Compounds Compound – 2 or more elements that are chemically bonded Chemical formulas show # of atoms each element contributes to compound – Ex : Na 2 NO 3 Na= ? N= ? O= ? Chemically stable when outermost energy level is filled

Atomic Structure Element/ Ion Atomic #Atomic Mass Mass Number ProtonsNeutronsElectrons H H+H C 7 3 Li Cl K Mg 2+ As 3- Ag Ag +1 S -2 U

Bonding Noble Gases – Far right column – Usually do not react w/ any other elements Chemical Bonds – Attractive forces that hold atoms together

Covalent Bonds Covalent Bond – forms when 2 atoms share 1 or more pairs of electrons

Ionic Bonds Ionic Bond – form when electrons are transferred from 1 atom to another

Energy Section 2

Activity List as many different types of energy as you can

Energy Energy – ability to do work

States of Matter

Chemical Reaction Chemical Reaction – change in which a substance is changed into 1 or more new substances – Reactants – substance or molecule that participates in a chemical reaction – Products – substance that forms in a chemical reaction

Rust Example 4Fe + 3O 2 = 2Fe 2 O 3 – Reactants? – Products?

Chemical Reactions in the Body How does your body acquire energy? – Proteins, sugars and fats in food provide energy – Energy released in body after breaking these down Metabolism – all chemical reactions that occur in an organism

Activation Energy Activation energy – amount of energy needed to start a reaction Catalyst – chemical substance that reduces amount of activation energy needed for reaction to take place

Activation Energy Vs. Catalyst

Enzymes Catalysts in the body Usually proteins or RNA

Oxidation Reduction Reactions What part of an atom helps transfer energy in a chemical reaction? Redox Reaction – r(x) where e- are transferred between atoms Oxidation Reaction – reactant loses e- and becomes (+) charged Reduction Reaction – reactant gains e- and becomes (-) charged

SECTION 2 REVIEW p Describe the effect of an enzyme on the activation energy in a chemical reaction. 4. Enzymes are biological catalysts. Explain what they do in living systems.

Water and Solutions Section 3

Activity Out of a human body, elephant, ear of corn, and a tomato, construct a list of which contains the highest percent of water to the least amount of water.

Answers – Tomato – 95% – Elephant – 70% – Corn – 70% – Human Body – 65%

Polarity Polar – partial charge that is produced because the total charge is unevenly distributed – Makes water great solvent because other polar things are attracted to it

Hydrogen Bonding Hydrogen Bond – force of attraction between a hydrogen molecule with a partial positive charge and another atom or molecule with a partial or full negative charge

Cohesion Cohesion – attractive force that holds molecules of a single substance together – Creates surface tension

Adhesion Adhesion – force between 2 particles of different substances – Creates capillary action

Temperature in Moderation Specific Heat - amount of heat a substance can absorb without raising its own temperature Day – water absorbs energy from sun and cools air w/o large increase in water temp. Night – cooling begins and warms the air

Solutions Solution – mixture in which 1 or more substances are uniformly distributed – Solute – substance being dissolved – Solvent – substance in which solute is dissolved – Various concentrations and becomes saturate when no more solute can dissolve Solute - salt Solvent - water

Acids and Bases Give examples of an acid and a base. OH - = hydroxide ion H = hydronium ion H 3 O + > OH - = acid H 3 O + < OH - = base (alkaline)

pH Scale Ranges from 0 – 14 – 0 – 6.9 = acid – 7 = neutral – 7.1 – 14 = base pH tested by litmus paper

Buffer Buffer – chemical that neutralizes acid or base – Overall pH of body = 7 pH stomach acid =2 pH intestinal fluid = 8 pH blood = 7.5 Buffers neutralize these and maintain body pH at 7