Biology 1107 Exam 1 Complete Questions And Answers

What is the difference between a compound and a molecule? - Answer-Chemical bond = molecule crystalline structure or atom by itself -- not a molecule 1 A molecule consists of two more atoms, which can be the same or different types of atom, that are linked by a chemical bond. A molecule of H2 or O2 is still a molecule, but not a compound. 2. A compound is usually a molecule as well. To be a compound, it has to have two different types of atoms, such as H2O. 3. Some compounds like NaCl are not molecules because they are linked together in a crystalline structure, rather than being molecularly bonded. mass number - Answer-Mass number is the total number of protons and neutrons in the most common isotope of an atom atomic number - Answer-Atomic number is only the number of protons in the nucleus of the atom, giving the atom it's identity as a particular element Identify the four elements that make up 96% of living matter - Answer-CHNO -- Carbon, Hydrogen, Nitrogen, Oxygen Draw and label a simplified model of an atom. Explain how this model misrepresents our understanding of atomic structure - Answer-The electrons don't actually go around in a circular orbit, but rather they appear in places around the nucleus that can be predicted with probability. Distinguish between each of the following pairs of terms: a. Neutron and proton - Answer-A neutron has a neutral charge and a proton has a positive charge. A neutron has slightly more mass than a proton. Distinguish between each of the following pairs of termsb. Atomic number and mass number - Answer-Mass number is the total number of protons and neutrons in the most common isotope of an atom Atomic number is only the number of protons in the nucleus of the atom, giving the atom it's identity as a particular element Distinguish between each of the following pairs of terms c Atomic weight and mass number - Answer-Mass number is an absolute -- it is the total number of protons and neutrons in an atom Atomic weight is the ratio of the average mass of the atom relative to 1/12 of the weight of a carbon atom. Explain how the atomic number and mass number of an atom can be used to determine the number of neutrons - Answer-Subtract atomic number from mass number and you will have the number of neutrons Explain how two isotopes of an element are similar. Explain how they are different. - Answer-The two isotopes of an element have the same number of protons but different numbers of neutrons What is the significance of an atoms valence in the construction of molecules and compounds? - AnswerIf the valence shell of an atom is filled, the element is stable and less likely to form a chemical bond with another atom. If the valence (outer) shell of an atom is missing one or more electrons, it is likely to fill those shells by sharing electrons with other atoms that also have unfilled valence shells. Define electronegativity. - Answer-A chemical property that describes the tendency of an atom or a functional group to attract electrons (or electron density) towards itself.[1] An atom's electronegativity is affected by both its atomic number and the distance that its valence electrons reside from the charged nucleus. The higher the associated electronegativity number, the more an element or compound attracts electrons towards it. Distinguish between nonpolar covalent, polar covalent and ionic bonds. - Answer-A nonpolar covalent bond is a bond where electrons are shared equally between two atoms. A polar covalent bond is a chemical bond where the shared electrons spend more time closer to the nucleus of the more electronegative atom.In an ionic bond, the electrons are completely transferred from one atom to another rather than shared. How Many Bonds Can an Atom Have? - Answer-Atoms with more than one unpaired electron can form multiple single bonds with multiple atoms or double or triple bonds with a single atom. Describe the electron-sharing continuum - Answer-The degree to which electrons are shared in chemical bonds forms a continuum, from equal sharing in nonpolar covalent bonds, to unequal sharing in polar covalent bonds, to the transfer of electrons in ionic bonds. Explain why strong covalent bonds and weak bonds are both essential in living organisms. - Answer-Strong covalent bonds are needed for living organisms so that organism bodies can form and hold together and not fall apart. Water is made of weak hydrogen bonds, which make it a solvent, and water is needed for life to dissolve nutrients for ingestion or wastes for excretion, to transport important chemicals or even be used as one. Explain how you would make up a one molar (1M) solution of ethyl alcohol.C2H6O. - Answer-2 carbons - 24 grams, 6 hydrogens, 6 grams, 1 oxygen, 14 grams, 24 + 14 + 6 = ethanol has a molar weight of 44. Ethanol is 0.789 grams per milliliter, so 55.8 milliliters of ethanol in 1 liter of water will create a 1 molar solution of ethanol. With the use of a diagram or diagrams, explain why water molecules are: a. polar - Answer-The water molecule is polar because the shared electrons are closer to the oxygen atom rather than the hydrogen atoms. With the use of a diagram or diagrams, explain why water molecules are: b. capable of hydrogen bonding with 4 neighboring water molecules - Answer-The oxygen atom is charged as 2- .And the two hydrogen atoms are charged as 1+ each.Therefore the oxygen atom can attract two hydrogen atoms of other two water molecules and the two hydrogen atoms can attrat two oxygen atoms of another two water molecules List four characteristics of water that are emergent properties resulting from hydrogen bonding. - Answer-1. Cohesive 2 Adhesive3. Denser as a liquid than as a solid 4. Able to absorb large amounts of energy