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Why Study Chemistry in Biology?

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Presentation on theme: "Why Study Chemistry in Biology?"— Presentation transcript:

1 Why Study Chemistry in Biology?

2 Ethylene gas ( hormone) stimulates the production of several enzymes
The enzyme that makes bananas sweet is called amylase. Amylase breaks down the starch in the banana fruit. When the starch is broken into its smaller sugar components, called glucose, the banana tastes sweet.

3 Prolong life by keeping warm temperatures - This is best explained by the banana’s slowed metabolic functions at a lower rate due to lower

4 I. Atoms Definition: smallest particle of an element
BOTH FOR LIVING AND NON LIVING Definition: smallest particle of an element


6 B. Composition C. If Neutral Atom: # protons = # electrons Proton +1 1
Subatomic Particle Charge Mass Location Proton +1 1 Nucleus Neutron Electron -1 1/1840 the mass of a proton Orbiting nucleus C. If Neutral Atom: # protons = # electrons

7 II. Elements Definition: substance that cannot be broken
down into other substances B. Biologically important elements i. Major: C H O N ii. Minor: Ca Fe Mg I Se P K Na Cl Symbol: usually from first letter or two of full name


9 Elements Con’t. Atomic Number: # of protons in nucleus
Mass Number Atomic Mass amu Atomic Number: # of protons in nucleus Backbone of life- 4 valence electrons make it easy to bond

10 E. Atomic Mass / Mass Number
Atomic mass: count of the total number of protons and neutrons in an atom's nucleus

11 F. Isotopes i. Definition: forms of the same element have same #
of protons but different # of neutrons Mass Number ii. Radioactive isotopes: An isotope having an unstable nucleus that decomposes spontaneously

12 G. Chemical Compounds i. Molecules definition: two or more atoms held together by COVALENT bonds

13 Compound definition: a substance containing two or more elements in a
fixed ratio Ex: H2O, NaCl

14 Decoding Chemical Formulas??
C6H12O6 Element subscript is the NUMBER of ATOMS So in this molecule, there are 6 carbon atoms, 12 hydrogen, and 6 oxygen

15 2H2O The number in front of H2O means two entire molecules of H2O
Think of it like 2 x (H20) Sooooo… how many total atoms of H are there? Of oxygen?

16 III. Bonding happy Atoms want to fill their outer energy levels to be
In order to do this, they will meet up with other atoms and either share or exchange electrons happy

17 A. Covalent Bonds Atoms share electrons so that both atoms fill their outer energy level

18 B. Ionic Bonds: gimme that electron!
Atoms transfer electrons, becoming (+) or (-) charged This attraction brings them together Ex: Na and Cl

19 Ions > An electrically charged atom

20 Carbon Has 4 electrons in outer level, needs 4 more to fill its orbital Hydrogen Has 1 electron, needs 1 to fill its orbital Can form ONE bond Can form FOUR bonds


22 IV. Water Human Composition: 65–90% water Plant Composition: 80-90%
Formula: H2O Bonds: i. Hydrogen bonds: the slightly (+) H atoms are attracted to nearby (-) O atoms, and develop a weak bond. ii. Covalent bonds: are shared between oxygen and hydrogen in a single molecule.

23 V. Water (con.’t) Water is a polar molecule:
i. Definition of polarity: molecule that has opposite electrical charges on opposite ends ii. Why? Oxygen does not share electrons equally- pulls them closer to itself, making it more negative and Hydrogen more positive

24 V. Water (con.’t) F. Unique molecule: i. Cohesion: 1. Definition: molecules of same kind stick to one another 2. Example: Surface tension; trees transporting water from roots to leaves

25 Adhesion: 1. Definition: attraction that occurs between unlike molecules 2. Example: Water molecules and cotton string.

26 Solutions: 1. Water is able to dissolve other polar and ionic compounds when mixed by causing the ions to break away and surround them. Ex.: Salt Water

27 Suspensions a. Definition: A heterogeneous mixture in which particles settle out of solvent-like phase some time after their introduction b. Example: oil & water iv. Boiling Point: water will boil at 100C or 212F

28 Acids and Bases i. A water molecule can react to form ions ii. An ion is when a molecule breaks down and the atoms get a charge 1. Example: H+ and OH-

29 iii. pH Scale 1. How? Scale of 0-14; each pH unit represents a tenfold change in the concentration of H+ ions 2. Acid definition: pH Base definition: pH 8-14

30 4. Buffer definition: substances that cause a solution to resist changes in pH.; works by accepting H+ ions when levels rise and donating H+ ions when levels fall, maintaining a constant pH a. Weak acid or base

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