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Biology Chapter2
| Question | Answer |
|---|---|
| What were the only two elements formed at the beginning of the world? | Hydrogen and Helium |
| What are the 3 biologically important groups of inorganic compounds? | 1) water 2) simple salts 3) simple acids & bases |
| What are organic compounds? | Large complex carbon containing molecules |
| What is an element? | A substance that cannot be separated into simpler parts by chemical reactions |
| Which 4 elements are responsible for 96% of an organism's mass? | 1) carbon 2) hydrogen 3) oxygen 4) nitrogen |
| What about an atom determines the way that it forms chemical bonds to produce complex compounds? | Its structure |
| What is an inorganic compound? | A simple substance that does not contain a carbon backbone. |
| What is a chemical symbol? | The first letter or first and second letters of the English or Latin name of the element |
| What are trace elements? | Elements required by the body in only very small amounts |
| What are the three main subatomic particles of an atom? | Proton, neutron, and electron |
| What is an atom? | The smallest portion of an element that retains its chemical properties. |
| What is matter? | Anything that has mass and takes up space |
| What are subatomic particles? | The components of atoms that are tiny particles of matter |
| Where are protons and neutrons found within an atom? | The nucleus |
| Where are electrons located? | Without a fixed location, they orbit the nucleus of the atom |
| What is an atomic number? | The number of protons within the nucleus of an atom |
| Why is the atomic number important? | It identifies the element to which the atom corresponds |
| What is a periodic table? | A chart of the elements arranged in order by atomic number |
| Why is the periodic table important? | It helps us understand the relationships between various elements |
| What is electron configuration? | The arrangement of electrons around the atom |
| What is the atomic mass unit? | The approximate mass of a proton or neutron; also called a dalton |
| What two things make up almost all the mass of an atom? | Protons and neutrons |
| What is the atomic mass? | The total number of protons and neutrons in an atom, expressed in atomic mass units (amu) or daltons |
| Why is the mass of an electron ignored? | Because it's too small |
| The common form of oxygen has 8 protons and 8 neutrons. What is its atomic number? | 8 |
| The common form of oxygen has 8 protons and 8 neutrons. What is its atomic mass? | 16 |
| What is an isotope? | An alternative form of an element with a different number of neutrons but th same number of protons and electrons. |
| Why do all isotopes of a given element have essentially the same chemical characteristics? | Because they have the same number of electrons |
| What happens to unstable isotopes? | They break down and decay to a more stable isotope (usually becoming a different element) |
| What is a radioisotope? | Unstable isotopes that spontaneously emit radiation; also called radioactive isotopes |
| How can radioactive decay be detected? | By autoradiography |
| What is autoradiography? | A method in which radiation causes the appearance of dark silver grains in photographic film |
| What are radioisotopes used for in medicine? | Diagnosis and treatment |
| What are some specific ways that radioisotope can be used in medicine? | To test thyroid gland function, to provide images of blood flow in the arteries, and treating cancer |
| What is an orbital? | The region in which electrons occur within an atom |
| Each orbital contains a maximum of how many electrons? | 2 |
| Why are orbitals depicted as electron clouds? | Because it is impossible to know an electron's position at any time, thus, the shaded areas give way to the probability that an electron is present there at any given instant. |
| What does the energy of an electron depend on? | The orbital that it occupies |
| Which electrons have the most energy? Those located closest or farthest away from the nucleus? | Farthest away |
| The most energetic electron is also known as... | The valence electron |
| What is a valence electron? | Electron in the outermost shell, valence shell |
| What do valence electrons play a key role in? | Chemical reactions |
| How can an electron move to an orbital farther away from the nucleus? | By gaining energy |
| How can an electron move closer to the nucleus? | By giving up energy |
| What is the chemical behavior of an atom determined by? | The number and arrangement of its valence electrons |
| When is the valence shell of hydrogen full? | When it has 2 electrons |
| When is the valence shell of any other atom full? | When it has 8 electrons |
| What are 3 things that an atom can do to achieve a full outer shell? | Lose, gain, or share an electron |
| The valence shell of all isotopes of an element are ________________ | Identical |
| How may two or more atoms combine? | Chemically |
| What is a chemical compound? | When two or more atoms of different elements combine |
| What is a molecule? | A stable particle formed by two or more atoms |
| All elements in the same vertical column (belonging to the same group) on the periodic table have the same what? | Chemical properties |
| Not all compounds are made up of... | Molecules |
| What is an example of a compound that is not made up of molecules? | Sodium Chloride |
| What is a chemical formula? | A shorthand expression that describes chemical composition of a substance |
| What are the 3 types of chemical formulas? | Simplest formula, molecular formula, and structural formula |
| What is simplest formula? | aka empirical formula, gives the smallest whole number ratios for the atoms present in a compound |
| What is molecular formula? | Subscripts that indicate the actual numbers of each type of atom per molecule |
| What is structural formula? | Shows type and numbers of atoms in a. molecule and their arrangement |
| How do you calculate molecular mass? | Multiply the subscript (number of atoms) times the atomic mass of that element and add the masses of all of the elements in the molecule to get the molecular mass. |
| Find the molecular mass of table sugar (sucrose), which has a molecular formula C12H22O11. | 342.30 molecular mass C12H22O11 = 12(mass of C) + 22(mass of H) + 11(mass of O) molecular mass C12H22O11 = 12(12.01) + 22(1.008) + 11(16.00) molecular mass C12H22O11 = = 342.30 |
| What is a mole? | The atomic mass of an element or the molecular mass of a compound, expressed in grams, one mole of any substance has 6.02x10^23 units |
| What are the two parts that make up a chemical equation? | Reactants and Product |
| What is a reactant? | The substances that participate in the reaction |
| What is a product? | The substance formed by the reaction |
| What does the arrow stand for in a chemical reaction? | yields |
| What are the numbers preceding the chemical symbols or formulas? | The coefficients |
| What is the purpose of the coefficient? | To indicate the relative number of atoms or molecules reacting |
| What is dynamic equilibrium? | The conditions of a chemical reaction when the rate of change in one direction is exactly the same as the rate of change in the opposite direction |
| What is a chemical bond? | A force of attraction between atoms in a compound |
| What is bond energy? | The energy necessary to break a chemical bond |
| What dictates how many bonds an atom can form? | The valence electrons |
| What are two types of chemical bonds? | Covalent and ionic bonds |
| What are covalent bonds? | A bond involving the sharing of electrons between two atoms in a way that results in each atom having a filled valence shell |
| A ________________ consists of two atoms joined together by a covalent bond. | Molecule |
| What are covalent compounds? | A compound in which atoms are held together by covalent bonds; covalent compounds consist of molecules |
| What is a single covalent bond? | When one pair of electrons are shared between two atoms |
| What are the functions of molecules dictated by? | Their geometric shape |
| What is a linear molecule? | A molecule that consists of two atoms |
| What is orbital hybridization? | A rearrangement of the orbitals in the valence shell that may occur when an atom forms covalent bonds with other atoms |
| What is electronegativity? | A measure of an atoms attraction for shared electrons in chemical bonds |
| What happens to electrons whose atoms have similar electronegativities? | The electrons are shared equally and the bond is described as nonpolar covalent |
| What happens to electrons if a covalent bond is formed between two different elements? | The electrons get pulled closer to the atomic nucleus of the element with great electron affinity |
| What is a polar covalent bond? | A bond with two dissimilar ends; partial positive charge and partial negative charge |
| Covalent bonds differ in their degree of ___________________ | Polarity |
| How can a molecule with one or more polar covalent bonds be polar even though it is electrically neutral as a whole? | A polar molecule has one end with a partial positive charge and another with a partial negative charge |
| What is an ion? | A particle with one or more units of electric charge |
| How does an atom become an ion? | If it gains or loses an electron |
| What happens with atoms that have 1, 2, or 3 electrons in its valence shell? | It tends to lose electrons to other atoms |
| What happens to the charge of an atom that loses electrons to other atoms? | It becomes positively charged because its nucleus chains more protons than the number of electrons orbiting the nucleus |
| What is a cation? | A particle with one or more units of positive charge, such as hydrogen and calcium |
| What happens with atoms that have 5, 6, or 7 electrons in its valence shell? | It tends to gain electrons from other atoms |
| What happens to the charge of an atom that gains electrons from other atoms? | It becomes more negatively charged |
| What is an anion? | A particle with one or more units of negative charge, such as chloride |
| What biological processes are cations and anions involved in? | Energy transformation, transmission of nerve impulses, and muscle contraction |
| How can a group of covalently bonded atoms become an ion? | By losing or gaining protons, derived from hydrogenous well as electrons |
| How can a group of atoms become a cation? | If it loses 1 or more electrons or gains one or more protons |
| How can a group of atoms become an anion? | If it gains on for more electrons or loses one or more protons |
| What is an ionic bond? | A bond that forms a a result of attraction between the positive charge of a cation and the negative charge of an anion |
| What is an ionic compound? | A substance consisting of anions and cations bonded by their opposite charges |
| What is a solvent? | A liquid that dissolves particles (the solute) |
| What is a solute? | The dissolved substance |
| What is a hydrogen bond? | A weak attractive force existing between a hydrogen atom with a partial positive charge and an electronegative atom (usually oxygen or nitrogen) with a partial negative charge |
| What is hydration? | The process of association of a substance with the partial positive and or negative charges of water molecules |
| What happens with hydrogen when it combines with with oxygen, or other electronegative atoms? | It acquires a partial positive charge because its electron spends more time closer to the electronegative atom |
| Although relatively weak, hydrogen bonds are strong when they are found in _______________________ | Large numbers |
| What is oxidation? | A chemical process in which an atom, ion, or molecule loses one or more electrons |
| What is reduction? | A chemical process in which an atom ,ion, or molecule gains one or more electrons |
| What does the term reduction mean in regards to a possible positive charge that is present? | Reduction refers to the fact that the gain of an electron results in the reduction of any positive charge that may be present |
| In what form is an electron transferred in a redox reaction? | Energy is transferred in the form of electrons |
| What is cohesion? | The property of sticking together |
| Why do water molecules have a strong tendency to stick to one another? | They have a strong tendency to stick to one another due to the hydrogen bonds among the molecule |
| What is adhesion? | The property of sticking to some other substance |
| What is capillary action? | The ability of water to move in a small-daiameter tubes as a consequence of its cohesive and adhesive properties |
| What is surface tension? | The attraction that the molecules at the surface of a liquid may have for one another |
| How would you describe molecules that are hydrophilic? | They interact readily with water. They have a greater affinity to water than with other molecules |
| How would you describe molecules that are hydrophobic? | They do not interact readily with water. They have less affinity for water molecules than they have for each other |
| Hydrophobic interactions happen between what kind of molecules? | They happen between nonpolar molecules |
| Hydrophobic molecules are _________________ and tend to ______________ together due to the hydrogen-bonded water molecules excluding them, in a sense "driving them together." | Insoluble, cluster |
| What kind of interaction explains why oil and water do not mix? | Hydrophobic interaction |
| What kind of bonding explains the way that water responds to changes in temperature? | Hydrogen bonding |
| Hydrogen bonds are _____________ or _______________ when changing from one state to the next. | Formed, broken |
| What should be added to make molecules move faster? | Heat energy |
| What is kinetic energy? | Energy of motion |
| What does the term heat refer to? | The total amount of kinetic energy in a sample of a substance |
| What is temperature? | A measure of the average kinetic energy of the particles |
| What is needed for molecules to move more freely? | Some of the hydrogen bonds need to be broken |
| What is heat of vaporization? | The amount of heat energy required to change 1g of a substance from the liquid phase to the vapor phase |
| What unit is heat of vaporization expressed as? | It is expressed as calories |
| What are calories? | The amount of heat energy required to raise the temperature of 1 g of water 1 degree Celsius |
| Why does water have a high heat of vaporization? | Because its molecules are held together by hydrogen bonds |
| What is specific heat? | The amount of heat energy that must be supplied to raise the temperature of 1 g of a substance 1 degree Celsius |
| What 4 elements are most abundant in living things? | Carbon, hydrogen, oxygen, and nitrogen |
| What determines the chemical properties of an atom? | The valence electrons |
| Through what reaction is the energy of an electron transferred? | Redox reaction |
| Acids are hydrogen ion ________________ | Donors |
| Bases are hydrogen ion _______________ | Acceptors |
| What is the purpose of the PH scale? | It measures the hydrogen ion concentration of a solution |
| How do electrons in different orbitals of the same electron shell compare with respect to their energy? | Electrons occupying different orbitals of the same electron shell are at the same principle energy level |
| Explain how the number of valence electrons of an atom is related to its chemical properties. | The number of valence electrons of an atom determines its ability to either lose, gain, or share electrons |
| Are all compounds composed of molecules? Explain. | No. A chemical compound consists of atoms of two or more different elements combined in a fixed ratio. Not all compounds are made up of molecules. For example, sodium chloride is not a molecule since sodium & chloride atoms are not covalenty bonded |
| What properties of a water molecule allows it to participate in the formation of a hydrogen bond? | Water molecules are formed by polar covalent bonds between oxygen & two hydrogen atoms. The region around the oxygen atom is slightly negative & region around hydrogen slightly positive, allowing hydrogen bonds to form |
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