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Chemistry. EVERY CHLORINE ATOM HAS 17 PROTONS, WITHOUT EXCEPTION, –HOWEVER, NOT EVERY CHLORINE ATOM HAS 18 NEUTRONS. –ATOMS WITH THE SAME NUMBER OF PROTONS.

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Presentation on theme: "Chemistry. EVERY CHLORINE ATOM HAS 17 PROTONS, WITHOUT EXCEPTION, –HOWEVER, NOT EVERY CHLORINE ATOM HAS 18 NEUTRONS. –ATOMS WITH THE SAME NUMBER OF PROTONS."— Presentation transcript:

1 Chemistry

2 EVERY CHLORINE ATOM HAS 17 PROTONS, WITHOUT EXCEPTION, –HOWEVER, NOT EVERY CHLORINE ATOM HAS 18 NEUTRONS. –ATOMS WITH THE SAME NUMBER OF PROTONS BUT CONTAIN DIFFERENT NUMBERS OF NEUTRONS ARE CALLED ISOTOPES. BECAUSE ISOTOPES OF AN ELEMENT HAVE DIFFERENT NUMBERS OF NEUTRONS THEY HAVE DIFFERENT MASS NUMBERS. EVERY CHLORINE ATOM HAS 17 PROTONS, WITHOUT EXCEPTION, –HOWEVER, NOT EVERY CHLORINE ATOM HAS 18 NEUTRONS. –ATOMS WITH THE SAME NUMBER OF PROTONS BUT CONTAIN DIFFERENT NUMBERS OF NEUTRONS ARE CALLED ISOTOPES. BECAUSE ISOTOPES OF AN ELEMENT HAVE DIFFERENT NUMBERS OF NEUTRONS THEY HAVE DIFFERENT MASS NUMBERS. ISOTOPES

3 ISOTOPES ARE CHEMICALLY ALIKE BECAUSE THEY HAVE IDENTICAL NUMBERS OF PROTONS AND ELECTRONS –IT’S THE ELECTRONS AND PROTONS THAT ARE RESPONSIBLE FOR CHEMICAL BEHAVIOR ISOTOPES ARE CHEMICALLY ALIKE BECAUSE THEY HAVE IDENTICAL NUMBERS OF PROTONS AND ELECTRONS –IT’S THE ELECTRONS AND PROTONS THAT ARE RESPONSIBLE FOR CHEMICAL BEHAVIOR proton neutron electron BERYLLIUM ISOTOPES BERYLLIUM ISOTOPES

4 EXAMPLE OF AN ISOTOPE Cl Cl NEUTRONS ATOMIC MASS 18 NEUTRONS ATOMIC NUMBER

5 IONS AN ELEMENT’S ATOMS ARE NOT ALWAYS NEUTRAL IN CHARGE. – WHEN AN ATOM LOSES OR GAINS ONE OR MORE OF ITS ELECTRONS IT BECOMES ION. AN ION THAT HAS MORE ELECTRONS THAN PROTONS HAS A NEGATIVE ELECTRICAL CHARGE AN ION THAT HAS FEWER ELECTRONS THAN PROTONS HAS A POSITIVE ELECTRICAL CHARGE AN ELEMENT’S ATOMS ARE NOT ALWAYS NEUTRAL IN CHARGE. – WHEN AN ATOM LOSES OR GAINS ONE OR MORE OF ITS ELECTRONS IT BECOMES ION. AN ION THAT HAS MORE ELECTRONS THAN PROTONS HAS A NEGATIVE ELECTRICAL CHARGE AN ION THAT HAS FEWER ELECTRONS THAN PROTONS HAS A POSITIVE ELECTRICAL CHARGE NOTE: IT’S THE PROTONS THAT DEFINE THE TYPE OF ATOM IT IS, BUT THE ELECTRONS DEFINE THE ATOM’S CHARGE.

6 SOME ATOMS GAIN ELECTRONS SOME ATOMS GAIN ELECTRONS O O ATOM’S IONIC CHARGE = # PROTONS - # ELECTRONS ATOM’S IONIC CHARGE = # PROTONS - # ELECTRONS

7 The Nerve Cells Sodium and potassium ions are used in the transmission of a nerve impulse.

8 Chemical Reactions Ø Living things undergo thousands of chemical reactions Ø Chemical equations represent chemical reactions Ø CO 2 + H goes to-----H 2 CO 3 (carbonic acid) is a sample Chemical Reaction in living things Ø Reactants are on the left side of the equation, while products are on the right side

9 Activation energy is required to start many reactions Energy must be added to the reactants for most chemical reactions to occur; called activation energy

10 Enzymes Enzymes are chemical substances in living things that act as catalysts & reduce the amount of activation energy needed Organisms contain thousands of different enzymes Most enzymes end with –ase (e.g. lipase is the enzyme that acts on lipids)

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12 Physical Properties of Water All of water’s UNIQUE properties are due to its POLARITY and HYDROGEN BONDING POLARITY H 2 O is a NEUTRAL molecule (p+ = e-) Oxygen attracts most of the e- toward its end and away from the hydrogen The OXYGEN END acts NEGATIVE, while the HYDROGEN END acts POSITIVE POLARITY (unequal distribution of charge)

13 HYDROGEN BONDING  Negative OXYGEN of ONE H 2 O molecule attracts the Positive HYDROGEN of ANOTHER H 2 O molecule

14 Bonding Strengths True chemical bonds like covalent, ionic, and metallic bonds are the strongest bonds Covalent bonds are the strongest force of attraction. They are stronger than ionic and metallic bonds. Hydrogen Bonding is a weaker type of bonding because it’s between molecules.

15 Acids and Bases The degree of acidity or alkalinity (basic) is important in organisms The force of attraction between molecules is so strong that the oxygen atom of one molecule can actually remove the hydrogen from other water molecules; called Dissociation H GOES TO----- H + + OH - OH - called hydroxide ion; H + called hydrogen ion

16 Free H + ion can react with another water molecule to form H 3 O + (hydronium ion) Acidity or alkalinity is a measure of the relative amount of H + and OH - ions dissolved in a solution Neutral solutions have an equal number of H + and OH - ions Acids have more H 3 O + ions than OH - ions; taste sour; and can be corrosive Bases contain more OH - ions than H 3 O + ions; taste bitter; & feel slippery

17 PH Scale Compares the relative concentration of H 3 O + ions and OH - ions Scale ranges from 0 to 14; 0-3 is very acidic; 7 is neutral; is very basic or alkaline

18 Buffers Control of pH is important to organisms Enzymes function only within a narrow pH range; usually neutral Buffers neutral acids or bases in organisms to help control pH

19 Organic Molecules Organic Compounds - have carbon bonded to other atoms (mostly Hydrogen) and determine structure/function of living things Inorganic Compounds – all others Organic compounds are made from a carbon skeleton which can – vary in length, – be branched or unbranched – have double bonds which vary in location – or may be arranged in rings.

20 Types of Organic Molecules MACROMOLECULES fall into four major groups 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic Acids


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