Chemistry Anatomy and Physiology | Tutorial Notes Chemistry LEARNING OBJECTIVES After study of today’s learning, the student will: 1. Describe the relationship among matter, atoms, and compounds 2. Describe how atomic structure determines how atoms interact 3. Explain how molecular and structural formulas symbolize the composition of compounds. 4. Describe three types of chemical reactions 5. Describe the differences among acids, bases, and salts 6. Explain the pH scale 7. Explain the function of buffers TUTORIAL OUTLINE I. Definitions A. chemistry – investigates the composition and interactions of matter B. matter – anything that has mass (weight) and occupies space. Forms of matter include solid, liquid, and gas C. Element – fundamental substance of matter D. Compound – combination of two or more different elements (eg. H2O, CO2) E. Atom – smallest functional particle of an element II. Bulk Elements – makeup over 99.9% of the body’s mass (see table 2.2) A. Oxygen – O B. Carbon – C C. Hydrogen – H D. Nitrogen – N E. Calcium – Ca 1
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Chemistry
Anatomy and Physiology | Tutorial Notes
Chemistry
LEARNING OBJECTIVES
After study of today’s learning, the student will:
1. Describe the relationship among matter, atoms, and compounds
2. Describe how atomic structure determines how atoms interact
3. Explain how molecular and structural formulas symbolize the composition of compounds.
4. Describe three types of chemical reactions
5. Describe the differences among acids, bases, and salts
6. Explain the pH scale
7. Explain the function of buffers
TUTORIAL OUTLINE
I. Definitions
A. chemistry – investigates the composition and interactions of matter
B. matter – anything that has mass (weight) and occupies space.
Forms of matter include solid, liquid, and gas
C. Element – fundamental substance of matter
D. Compound – combination of two or more different elements (eg. H2O, CO2)
E. Atom – smallest functional particle of an element
II. Bulk Elements – makeup over 99.9% of the body’s mass (see table 2.2)
A. Oxygen – O
B. Carbon – C
C. Hydrogen – H
D. Nitrogen – N
E. Calcium – Ca
F. Phosphorus – P
G. Potassium – K
H. Sulfur – S
I. Chlorine – Cl
J. Sodium – Na
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K. Magnesium – Mg
III. Trace Elements – less than 0.1% (see table 2.2)
A. Cobalt – Co
B. Copper – Cu
C. Fluorine – F
D. Iodine – I
E. Iron – Fe
F. Manganese – Mn
G. Zinc – Zn
IV. Atomic Structure (see figure 2.1)
A. Subatomic Particles
1. Proton - Charge of one proton = +1
Relative mass of one proton = 1
2. Neutron - Charge of one neutron = 0 (uncharged)
Relative mass of one neutron = 1
3. Electron - Charge of one electron = -1
Relative mass of one electron = 0
Nucleus – contains protons and neutrons
Electrons orbit the nucleus in distinct electron shells
B. Atomic Charge – number of protons equals the number of electrons, so the charges
cancel and the atom has no net charge (It is electrically neutral)
C. Atomic Number – number of protons in an atom of a particular element.
Each element has a unique atomic number
1. Hydrogen has 1 proton, therefore its atomic number = 1
2. Carbon has 6 protons, therefore its atomic number = 6
3. The atomic number of Oxygen = 8. How many protons does it have?
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Chemistry
D. Atomic Weight (Mass) – number of protons + number of neutrons in an atom of an element.
1. The atomic weight of Carbon with 6 protons + 6 neutrons + 6 electrons = 12
*Remember the weight of electrons is so small we don’t calculate it in the atomic weight!
V. Isotopes
A. Isotopes are atoms of an element with different number of neutrons. They have the same atomic number (number of protons) but different atomic weights.
B. Example of isotopes
1. Carbon (C) has three isotopes
a. Carbon-12 has 6 protons and 6 neutrons. About 99% of Carbon is Carbon-12
b. Carbon-13 has 6 protons and 7 neutrons. About 1% of Carbon is Carbon-13
c. Carbon-14 has 6 protons and 8 neutrons. Less than 1% of Carbon is Carbon-14
C. Radioactive Decay
1. The nucleus of an unstable isotope may react to form a more isotope, releasing energy
in the process.
2. Decay of Carbon-14
a. Carbon-14 has 6 protons and 8 neutrons
b. A neutron from C-14 may decay into a proton and electron
c. The additional proton changes the atomic number from 6 into 7, thus
converting Carbon into Nitrogen
VI. Molecules and Compounds
A. Molecule – particle of two or more atoms chemically joined by covalent bond.
1. Compound – molecule of two or more different elements
a. Water molecule H2O (molecular formula)
b. Carbon Dioxide molecule CO2
2. Molecule of an element – molecule of identical elements
a. Hydrogen molecule H2
b. Nitrogen molecule N2
c. Oxygen molecule O2
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VII. Properties of Electrons
A. Electron Shells
1. 1st shell holds 2 electrons (closest to the nucleus)
2. 2nd shell holds 8 electrons
3. 3rd shell holds 8 electrons
B. Electron rules
1. Octet rule – atoms react in a way to fill the outermost shell completely. Because the 2nd and 3rd shell hold 8 electrons, we think of this as the octet rule.
2. Electron pairing – electrons tend to react to form electron pairs. That is, lone electrons tend to react to pair with other lone electrons.
VIII. Ions
A. Ion is an atom that gains or loses electrons and becomes electrically charged.
B. Cation
1. ions that tend to loose electrons are called cations
2. cations are positively charged
3. Example: Sodium tends to release 1 electron to make the sodium cation (Na+)
C. Anion
1. ions that gain electrons are called anions
2. anions are negatively charged
3. Example: Chlorine tends to accept 1 electron to make the chloride anion (Cl-)
IX. Chemical Bonds
A. Ionic Bonds (see figure 2.4)
1. Ions with opposite charges attract each other forming ionic bonds.
2. Ionic bonds are formed between Cations (+) and Anions (-)
3. Example: Na+ and Cl- unite to form NaCl (sodium chloride)
4. Ionic bonds tend to form well-organized arrays (crystals) because ions attract opposite
charges from all directions.
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Chemistry
B. Covalent Bonds (see figure 2.5)
1. Covalent bonds are formed when atoms share electrons, rather than gaining or losing
them.
2. Covalent bonds may be single, double, or triple Structural formula
a. Single bond: atoms share 1 pair of electrons H—H
b. Double bond: atoms share 2 pairs of electrons O=C=O
c. Triple bond: atoms share 3 pairs of electrons N≡N
3. Polarity
a. Non-polar bonds
Atoms share electrons equally, so the molecules are uncharged
non-polar bonds are mostly water insoluble
hydrocarbons (carbon and hydrogen) are an important group of
non-polar molecules
b. Polar bonds
Unequal sharing of electrons
One atom has a higher affinity for the electrons than the other atoms
polar bonds are common between oxygen and hydrogen (or nitrogen and hydrogen)
The oxygen end tends to be negatively charged, while the hydrogen end tends to be positively charged.
C. Hydrogen Bonds (see figure 2.8)
1. Attraction between a slightly positive hydrogen end of one molecule and a negative
oxygen or nitrogen end of a different molecule.
2. Hydrogen bonds are relatively weak, but can form ice at 0°C
3. Hydrogen bonds maintain the structure of proteins and DNA