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75 Cards in this Set
- Front
- Back
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Who were the first to develop the atomic theory?
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Greeks
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Which element is found in the highest concentration in humans as % of weight?
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Oxygen
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Why was the atomic theory proposed by the Greeks incorrect.
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To the Greeks the word "atomos" means literally "indivisible." It was over 2,000 years later, in the 20th Century, with the use of particle accelerators that atoms were smashed together at extreme speeds and the atom was broken into many subatomic particles.
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Of the many subatomic particles, which three do we study in this course?
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Protons, neutrons, electrons
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What does "AMU" stand for in chemistry?
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Atomic mass unit
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What is the amu value for a proton?
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1
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What is the amu value for a neutron?
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1
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What is the amu value for an electron?
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For all practical purposes we pretend it does not have mass. Clearly an electron does have mass. It mass is 9.109 x 10-28 g. (-28 is a superscript)
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What is the charge of a single proton?
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+1
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What is the charge of a single neutron?
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Neutrons do not have a charge - hence their name.
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Define isotope.
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An isotope is an atom or molecule that has the same atomic number but a different atomic weight due to a differing number of neutrons.
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Give three uses for radioactive isotopes.
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1. radioactive dating
2. environmental monitoring 3. medical testing |
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What are the two isotopes of hydrogen?
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Deuterium and tritium
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What is the meaning of half-life in reference to radioisotopes?
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A 1/2 life is the amount of time that passes for 1/2 of the isotope to be emitted. For carbon 12 it is 5,730 years. Carbon dating can be used for samples between 500 to 75,000 years but no more.
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Define isomer.
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An isomer is a molecule that has the same molecular formula, but has a different structural formula.
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What are three common isomers of hexose monosaccharides?
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Glucose, fructose, galactose
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Define what is meant by a chemical bond.
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A chemical bond is a union between atoms formed when they; give up electrons, gain electrons, or share electrons.
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What are the three main types of chemical bonds?
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Covalent, ionic, hydrogen
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Which of the three types of chemical bonds is the strongest?
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Covalent
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Which of the three types of chemical bonds is most important to organic life?
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Covalent
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Which type of bond is formed when electrons are either lost or gained?
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Ionic
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What is an ion?
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a charged atom or molecule
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How are ions formed?
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when electrons are either gained or lost
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What type of ion is formed when electrons are gained?
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negative ions (because additional negative charges are being added)
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What type of ion is formed when electrons are lost?
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Positive ions (because when negative charges are lost, what remains is net positive)
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In human physiology what are ions called?
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Electrolytes
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Name three of the most common human electrolytes?
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potassium (K), sodium (Na) and calcium (Ca)
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What are the names of the three energy levels closest to the nucleus of an atom?
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K, L, M (there are many other levels too - N, O, P, Q, etc.)
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How many electrons can the "K" energy level hold?
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2
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How many electrons can the "L" energy level hold?
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8
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How many electrons can the "M" energy level hold?
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18
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What energy level is closest to the nucleus?
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K
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What rule needs to be followed when distributing electrons into energy levels?
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Always begin by filling the K level first and complete each level before moving to the next.
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How do atoms gain stability?
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by completing their outermost energy level
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Why are some atoms un-reactive - like helium?
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They have a filled outer energy level.
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How is an ionic bond formed?
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Ionic bonds are formed when electrons are lost or gained forming ions.
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What is the formula for common table salt?
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NaCl
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What type of chemical reactions are caused when electrons are lost?
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oxidation reactions
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What type of chemical reactions are caused when electrons are gained?
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reduction reactions
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Give the electron distribution of Carbon - atomic number 6.
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K=2, L=4
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Give the electron distribution of sodium (Na), atomic number 11.
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K=2, L=8, M=1
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Will atomic number 11 form positive or negative ions - and why?
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Positive ions; because K=2, L=8, M=1. The single electron in M will be lost to gain stability. Once lost, M no longer exists, and L remains full with 8 - and the positive ion is formed because of the loss on one electron.
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Give the electron distribution for chlorine, atomic number 17.
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K=2, L=8, M=7
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What type of ion will form by atomic number 17?
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Negative - because a single electron with be attracted .
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What type of bonding involves the sharing of electrons?
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Covalent bonding
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What are the two types of covalent bonds?
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Polar and nonpolar
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What is the covalent bond called in which electrons are equally shared?
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Nonpolar
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What is the covalent bond called in which electrons are NOT shared equally?
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Polar
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What type of covalent bond does water represent?
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Polar
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What type of bond is formed by adjoining water molecules?
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Hydrogen bonds
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Of the three major bond types, which is the weakest?
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Hydrogen bonds
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Of the three major bond types, which is the strongest?
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Covalent
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Which is stronger, a covalent bond, or an ionic bond?
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Covalent
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What is the definition of specific heat?
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Specific heat is the amount of heat (energy) needed to raise one gram of water one degree Celsius.
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Water has high heat of vaporization. What does that mean?
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Heat of vaporization is the heat of vaporization is the amount of heat necessary to vaporize or evaporate one gram of liquid water.
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In biology, what is the universal solvent?
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Water
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What is a simple definition of a solute?
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something that dissolves in water (solvent)
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It is said that water molecules are cohesive. What does that mean?
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Water molecules cling together because of hydrogen bonding. The hydrogen bonding causes the cohesion.
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It is said that water molecules are adhesive. What does that mean?
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Adhesion is due to water's positive and negative poles, allowing it to adhere to other polar surfaces.
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Give the definition of a calorie.
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A calorie is the amount of energy required to raise the temperature of 1 g of water 1ºC.
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What do you call substances that dissolve in water?
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Solutes
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What does hydrophilic mean?
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Hydrophilic means attracted to water. (hydro - water, philic - loving)
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What does hydrophobic mean?
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Hydrophobic means repelled by water. (hydro - water, phobic - hating)
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In reference to properties of water, what is the difference between cohesion and adhesion?
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Cohesion is caused by water molecules being attracted to each other because of polar covalent bonding. Adhesion is occurs when water molecules position their negative poles so that they adhere to polar surfaces.
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Why does solid water (ice) float rather than sink to the bottom?
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Ice floats because it is less dense structurally than liquid water. This open structure (more open than liquid water) makes ice float.
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The pH scales ranges from what number to what number?
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0 to 14
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What is a pH of 7.0 called?
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Neutral
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What is a pH of less than 7.0 called?
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An acid
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What is a pH of over 7.0 called?
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Base or alkaline
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Define an acid.
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An acid is a substance that dissociates in water, releasing hydrogen ions (H+).
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Define a base.
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A base is a substance that dissociates in water releasing hydroxide ions (OH-).
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What is a buffer?
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A buffer is a substance that keeps pH within normal limits.
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What is the pH of most bodily fluids?
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7.4 - slightly alkaline (basic)
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What is an organic substance?
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A substance which contains, as a minimum, carbon, and usually hydrogen as well.
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Is a carbon atom stable?
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No a carbon atom is atomic number 6. There are 2 electrons in the K energy level, and 4 electrons in the L energy level. Since the other shell is not filled it is unstable.
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