1. Chemistry for Life Chapter 2
Dr Bill Stafford
2016

2. State Standards
CLE Distinguish among the structure and function of the four major organic macromolecules found in living things.
CLE Describe how enzymes regulate chemical reactions in the body.

3. I Can Statements I Can Statements
1. I can list and describe the three parts of the atom.
2. I can relate acidity and basicness to the pH scale.
3. I can discuss chemical structure of water and relate it to the role in living things.

4. Chemistry for Life – Chapter 6
Elements – substances that cannot be broken down into simpler substances
Examples – Hydrogen
Carbon
Oxygen
Nitrogen

5. Chemistry for Life – Chapter 6
Element
90 occur naturally – 25 essential for living organisms
4 elements make up 96% of the human body – CHON
1. Carbon – C
2. Hydrogen – H
3. Oxygen – O
4. Nitrogen – N
1-2 letter abbreviation
Trace elements – found in small amounts in living organisms

6. Chemistry for Life – Chapter 6
Elements
Elements come into plants through the roots.
Elements come into animals from the food they eat.

7. Chemistry for Life – Chapter 6
Atoms – smallest particle that has the characteristics of the element
Examples – Hydrogen and oxygen
A. Parts of an atom
1. Nucleus – center of the atom
a. Proton – has a positive (+) charge – the number of protons defines the element – atomic number
b. Neutron – has no charge – neutral – usually the same number as protons

8. Chemistry for Life – Chapter 6
Atoms
A. Parts of an atom
2. Electron cloud – made up of electrons that have little mass and a negative (-) charge
B. Elements usually have an equal number of protons and electrons. This gives the atom no net charge.
Examples: oxygen - 8 protons and 8 electrons
hydrogen – 1 proton and 1 electron
carbon – 6 protons and 6 electrons

9. Summary of Subatomic Particles:
Particle Name
Location
Charge
Mass
Electron
Orbitals -1 ~0
Proton
Nucleus +1 1
Neutron
No Charge

10. Chemistry for Life – Chapter 6
Atoms
C. Atomic mass – total number of protons and neutrons
Examples: carbon 6 protons + 6 neutrons = atomic weight of 12
Example: Carbon 6 protons and 6 neutrons
Atomic number – 6 (6 protons)
Atomic mass – 12 ( 6 protons and 6 neutrons)
All atoms with 6 protons are always carbon atoms

11. Atoms differ in __________ of _______, ________,& _______
NUMBERS
PROTONS
NEUTRONS
ELECTRONS
Image from:

12. Periodic Table Notation:
It is the number of protons an element has which determines what element it is.
Carbon = 12
Hydrogen = 1
Oxygen = 16
Nitrogen = 17
Neutral atoms have EQUAL numbers of protons (+) and electrons (-)

13. Chemistry for Life – Chapter 6
Isotopes – Atoms of an element with a different number of neutrons.
Examples:
C-12 – 6 protons and 6 neutrons – atomic weight of 12
C-14 – 6 protons and 8 neutrons – atomic weight of 14

14. Chemistry for Life – Chapter 6
Compounds – 2 or more different atoms chemically joined by chemical bonds.
A. Examples: H2O and CO2
B. The compound has different properties than either element (atom) that makes it up – H2O (water) is liquid and hydrogen (H) and oxygen (O) are gases
Molecule -2 or more atoms chemically joined – can be different atoms or the same – O2 or H2O – I will use both words – compound and molecule

15. ATOMS CAN ______TOGETHER TO _____________________
JOIN
MAKE MOLECULES
Ex:
Joining 2 HYDROGEN atoms with 1 OXYGEN atom makes one ______ molecule.
WATER
A _______________ tells _________ of and __________ atoms are in a molecule
EX: ________
what kind
chemical formula
how many
H2O

16. ELECTRON / ENERGY LEVEL RULES:
Atoms seek to have a “full” outermost energy level.
All chemical formulas and reactions happen to accomplish this
Filled outer energy levels mean the substance is inert or stable (won’t react)

18. Chemistry for Life – Chapter 6
Chemical bonds – What holds compounds together
A. Covalent bonds – the atoms share electrons to fill the outer shells  leads to a more stable state
Examples: - fats, carbohydrates, proteins, water
Very common in living organisms
B. Ionic bonds – one atom receives an electron to get a negative charge and one atom gives up an electron to get a positive charge – the atoms are held together by their opposite electrical charges
Examples: Table salt – NaCl
Very rare in living organisms

19. Interactions of matter:
Atoms interact through the process of chemical bonding.
Bonding is determined by the number of electrons found in the outermost energy level of an atom (valence electrons)
Bonding Involves the transfer & sharing of electrons between atoms.
Covalent (sharing of electrons)
Ionic (transfer of electrons)

21. Ionic Bonds: Table salt (sodium chloride) forms by ionic bonding
Sodium loses 1 electron = +1 ion (Na+1)
Chlorine gains 1 electron = -1 ion (Cl-1)
Compound is NaCl

22. Summary of Ionic & Covalent Bonds

23. Chemistry for Life – Chapter 6
Ions – electrically charged atoms – give up or acceppts an electron
A. Negative ion (-) – anion – accepts an electron
B. Positive ion (+) – cation – gives up an electron

24. KEY CONCEPT Water’s unique properties allow life to exist on Earth.

25. Water Importance of water 1. Solvent of living organisms
2. Material transport – blood in animals and sap in plants
3. Makes up 70-95% 0f all organisms

26. Life depends on hydrogen bonds in water.
Water is a polar molecule.
Polar molecules have slightly charged regions. O H _ +
Nonpolar molecules do not have charged regions.
Hydrogen bonds form between slightly positive hydrogen atoms and slightly negative atoms.

27. Water (continued)
Water is a polar molecule – a compound with unequal distribution of electrical charge
1. Electrons (negative) closer to oxygen due to 8 (+) protons in nucleus
2. Positive charge on hydrogen side and negative charge on oxygen side
3. Forms weak hydrogen bonds – attraction of opposite charges

28. Hydrogen bonds are responsible for four important properties of water.
high specific heat
cohesion
Adhesion
Ice floats –
less dense

29. Water (continued)
Important properties of water due to polarity of water molecule
1. Cohesion and adhesion  capillary action  transport of water from roots to leaves
2. Surface tension – allows things to float
3. Resists temperature change – homeostasis
4. Water expands when it freezes  ice floats  makes soil

30. Chemistry for Life – Chapter 6
Mixture and solutions
A. Mixture – a combination of substances where each substance retains (keeps) its own properties and can be easily separated.
B. Solution – Two or more substances that are mixed evenly together – solution has new properties different than either ingredient – hard to separate
1. Solvent – dissolving substance – usually water
2. Solute – Substance that is dissolved – usually a solid
The concentration of each is critical

32. “Like dissolves like” HYDROPHILIC
____________________ means “water loving”
_________ groups/molecules try to _________ and touch water or
__polar___molecules
be near
other polar
Water makes a great solvent in
living things because so many
molecules found in living things
are polar or have a charge.

33. “Like dissolves like” HYDROPHOBIC
“Like dissolves like”
HYDROPHOBIC
_________________ means “water fearing”
___________ groups/molecules try to _________ other __________ molecules and __________ ________ molecules
NON-polar
be near
NON-polar
away from
polar
Oil based paints dissolve
in solvents such as
turpentine
. . . not water.

34. Chemistry for Life – Chapter 6
Acids and bases
A. Acids – results in excess of H+ ions in water
Examples
B. Bases – results in excess of OH- ions or decrease of H+ ions
C. pH scale – shows acidity or basic quality of substance
1. Below 7 is acidic
2. 7 is neutral – not acidic or basic
3. Above 7 is basic

35. Chemistry for Life – Chapter 6
Acids and bases
C. pH scale
A substance with an extreme pH close to 1 or 14 is very caustic and damaging

36. Hydrogen Ions (H+) More H+ = more acidic H+ acidic
The number of ____ ions determine how _______ a solution will be. H+
acidic
More H+ = more acidic