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Presentation on theme: "CHAPTER 6 – THE CHEMISTRY OF LIFE"— Presentation transcript:

SECTION 6.1 – Atoms + their Interactions p

2 Atoms: The Building Blocks of Rocks - and You…
Both living and nonliving things are composed of the basic building blocks called ATOMS

3 Elements Definition A substance that can’t be broken down into simpler chemical substances Examples: Gold Tungsten Helium

4 Elements Only about 25 elements are essential to living things
Four make up 96% of a human body: Carbon Hydrogen Oxygen Nitrogen

5 Elements Elements are identified by a symbol Trace elements C – Carbon
Ca – Calcium Trace elements Elements present in small amounts in living things Examples: Iron Copper Zinc Iodine

6 Atoms: The Building Blocks of Elements
Definition The smallest particle of an element that has the characteristics of that element Basic building block of all matter

7 Atom - Structure Nucleus Center of the atom Contains:
Protons Positively charged particles (p+) Neutrons Particles with no charge (n0) Nucleus has a positive charge

8 Atom - Structure Elements differ in the number of protons each has
Example: Iron vs. Aluminum

9 Atom - Structure Electrons
Small, negatively charged particles that surround the nucleus (e-) Held in place by its attraction to p+ in nucleus Found in electron clouds # electrons is energy levels 1st – 2 2nd – 8 3rd – 18

10 Electron energy levels

11 Isotopes Definition Atoms of the same element that have different numbers of neutrons Examples: C-12 C-13 C-14

12 Isotopes Uses of isotopes:
Some are radioactive and therefore can be used in radiation treatments Can be used to estimate age of objects (radioactive dating)

13 Compounds + Bonding Compound
A substance composed of atoms of two or more different elements that is chemically combined Example: TABLE SALT - NaCl

14 Compounds + Bonding Most elements in nature are found in compounds
Atoms combine with other atoms to become stable Outermost energy level is filled Is this atom stable?

15 Types of Bonds Covalent When two or more atoms share electrons
Example: Hydrogen, H2 Most compounds in organisms have covalent bonds Sugars, fats, proteins, + water

16 Types of Bonds Molecule
A group of atoms held together by a covalent bond Example: WATER

17 Types of Bonds Ionic bond
The attractive force between two ions of opposite charge Formed by combining ions – a charged particle made of atoms Opposites attract – “+” like “-” Example: Table Salt

18 How an Ionic bond forms…

19 Chemical Reactions Occurs when bonds are formed or broken, causing substances to recombine into different substances Occurs within cells Metabolism All the chemical reactions that occur within an organism


21 Chemical Reactions Chemical reactions are represented by writing CHEMICAL EQUATIONS Example – the formation of water 2 H2 + 1O2 2 H2O Reactants Products Coefficients Indicates the # of molecules Subscripts Indicates the # of atoms Equations must be BALANCED!!!

22 Mixtures + Solutions Mixture
A combination of substances in which the individual components retain their own properties Example: Sugar + Water Trail Mix

23 Solutions Definition A mixture in which one or more substances are distributed evenly in another Parts: Solute Substance that gets dissolved Solvent Substance doing the dissolving

24 Concentration Definition
Amount of solute dissolved in fixed amount of solvent The more solute dissolved in the solvent, the greater the concentration of the solution

25 Acids + Bases Chemical reactions can occur only when conditions are right A reaction may depend upon: Available energy Temperature Concentration of substance pH

26 Acids + Bases pH A measure of how acidic or basic a solution is
Scale ranges from 0 to 14

27 Acids + Bases Acid Substance that forms H+ ions in water
pH range – below 7 Typically sour to taste; can be corrosive Examples: Lemon Tomato Stomach acid

28 Acids + Bases Neutral Substance that has pH value = 7 Example:
Pure water

29 Acids + Bases Base Substance that forms hydroxide ions (OH-) in water
pH range – above 7 Typically bitter to taste; feels slippery Examples: Egg Drain cleaner Antacid



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