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23 Cards in this Set
- Front
- Back
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Octet Rule
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8 electrons in the outer shell (valence orbit)
If 8 electrons, it is stable and will not enter into chemical reactions Krypton is an example - inert element |
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Inert elements
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Argon (Ar), Neon, (N), Xenon (Xe), and Radon (Rn) satisfy the octet rule
He - has only 2 electrons in its valence shell, but it's complete, so it is also inert |
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Octet Rule
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Elements with less than half the octet number of electrons (4 or less) at as electron donors - lose electrons - metals - become positively charged
Those with more than 4 electrons in the valence shell act as non-metals and gain electrons - become negatively charged |
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Bonding
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Ionic
Covalent Hydrogen |
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Ionic Bonding
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Non-covalent
Characterized as a charge - charge interaction Electronegativity is one of the forces that affects how atoms interact with each other Ionic bonding when electronegativity difference between atoms is greater than 1.7 Electrons are transferred from one atom to another to satisfy the octet rule |
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Ionic Bonding
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NaCl is an example
Na Cl NaCl - which is an ionic substanceThe electronegativity difference between Na and Cl is 2.3 Other forces affect bonding too, but not discussed in this course |
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Ionic Bonding
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see pic pg. 10
Electron is transferred from Na to Cl Crystal lattice is result - when put it in water, it dissolves |
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Covalent Bonding
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Sharing of electrons between atoms
Molecular substance is the result There are more molecular substances than ionic substances Atoms that bond covalently have an electronegativity difference of less than 1.7 Can have single, double, or triple covalent bonds |
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Electronegativity Rules
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When the difference in electronegativity is between 0.0 - 0.4 electrons are shared equally (H2 and O2)
0.5 - 0.9 Electrons are shared unequally; Covalent non-polar if molecule is uniform and symmetrical (CH4 and CCl4 1.0 - 1.6 Electrons are shared unequally and bond is covalent polar if molecule is non-uniform and asymmetrical (ClCh3) 1.7 and greater Electrons are transferred - ionic bond (NaCl) |
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Hydrogen Bond
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A type of non-covalent molecular interaction resulting in a bond formed between a positive H from one molecule and a negatively charged O or N from another molecule
H has a very small share of the electron pair in the bond; highly polar |
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Hydrogen Bonds
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The oxygen for a H bond is frequently from a carbonyl group
The nitrogen for a H bond is frequently part of the amine group Hydrogen bonds form rapidly and are maintained only briefly (10 - 11 seconds half life) Hydrogen bonding is important biochemical;y and is responsible for waters 's lattice structure |
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Hydrogen Bonds
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Proteins of our tissues and nucleic acids (DNA & RNA)in our cells are good examples of hydrogen bonds
In water, hydrogen bonds deal with dipole-dipole interaction of water molecules see pg. 12 |
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Hydrogen Bonds
Water |
Molecules are constantly moving until it freezes
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Isotopes
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Atoms of an element witha varying atomic mass due to a different number of neutrons
Protons (atomic number) are always the same for an element |
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Isotopes
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Nuclear medicine uses P
RBC (red blood cell) studies use Fe |
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Radioisotopes
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Not stable; emit energy
Emit radioactive particles that are lethal (damage) cells, tissues, and organisms 1/2 life is the time it takes one half of the radiactive mass to decay 0 can range from seconds to millions of years |
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Chemical Reactions
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All chemical reactions in the body make up metabolism
Metabolism provides for the capture, storage, storage, and release of energy Work + movement of an object or change in its physical structure Energy + capacity to perform work Kinetic energy is energy of motion Potential energy is stored energy resulting from position Conversions are not 100% efficient, resulting in the release of heat ( mass to energy) |
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Metabolism
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Sum of all reactions
Through catabolism (breakdown of complex molecules) cells gain energy Anabolism uses energy - synthesis of new molecules |
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Basic Chemical Reactions
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Synthesis
Decomposition Exchange Reversible |
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Synthesis
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N + 3H NH (ammonia)
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Decomposition
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CH C (carbon) and 4H (hydrogen)
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Exchange
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HCl + NaOH NaCl (salt) + H 0(water)
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Reversible
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H 0 +C0 H CO (carbonic acid)
At equilibrium, the rates of the 2 reactions proceed in balance |
