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Biology lecture ch 2
Flash cards for Campbell and Reece Biology 8th Ed. (ch 2)
| Question | Answer |
|---|---|
| Anything that takes up space and has mass | Matter |
| A substance that cannot be broken down to other substances by chemical reactions | Element |
| A substance consisting of two or more different elements in a fixed ratio. Ex. NaCl | Compound |
| Elements that are required by an organism in only minute quantities | Trace elements |
| The smallest unit of matter that still retains the properties of an element | Atom |
| A subatomic particle having no electrical charge, found in the nucleus of an atom | Neutron |
| A subatomic particle with a single positive electrical charge, found in the nucleus of an atom | Proton |
| A subatomic particle with a single negative electrical charge. Moves around the nucleus of an atom. | Electron |
| Dense core at the center of an atom | atomic nucleus |
| A measure of mass for atoms and subatomic particles; the same as the atomic mass unit, or amu. | Dalton |
| The number of protons of an element | Atomic number |
| The sum of protons plus neutrons in the nucleus of an atom | Mass number |
| the total mass of an atom, which is the mass in grams of 1 mole of the atom | Atomic mass |
| One of several atomic forms of an element, each with the same number of protons but a different number of neutrons | Isotope |
| An isotope in which the nucleus decays, giving off particles and energy. | Radioactive isotope |
| The capacity to cause change--for instance, by doing work | Energy |
| The energy that matter possesses because of its location or structure | Potential energy |
| An energy level of electrons at a characteristic average distance from the nucleus of an atom | Electron shell |
| The electrons in an atom's outermost shell | Valence electrons |
| The outermost electron shell of an atom | Valence shell |
| The three-dimensional space where an electron is found 90% of the time | Orbital |
| An attraction between two atoms, resulting from the sharing of outer-shell electrons or the presence of opposite charges on the atoms | Chemical bond |
| Consists of two or more atoms held together by covalent bonds | Molecule |
| A bond that consists of one pair of shared electrons | Single bond |
| A type of molecular notation in which the constituent atoms are joined by lines representing covalent bonds | Structural formula |
| A type of molecular notation representing the quantity of constituent atoms, but not the nature of the bonds that join them | Molecular formula |
| The sharing of two pairs of valence electrons by two atoms | Double bond |
| The bonding capacity of a given atom | Valence |
| The attraction of a particular kind of atom for the electrons of a covalent bond | Electronegativity |
| A bond in which electrons are shared equally | Nonpolar covalent bond |
| A bond in which electrons are not shared equally | Polar covalent bond |
| A charged atom | Ion |
| A positively charged ion | cation |
| A negatively charged ion | Anion |
| The attraction between a cation and an anion | ionic bond |
| A compound formed by an ionic bond | ionic compound |
| A bond that forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom. | Hydrogen bond |
| Weak attractions between molecules or parts of molecules that result from localized charge fluctuations. | Van der Waals interactions |
| In a chemical reaction, the state in which the rate of the forward reaction equals the rate of the reverse reaction, so that the relative concentrations of the reactants and products do not change with time. | chemical equilibrium |
| How many elements occur in nature? | 92 |
| How many elements are known to be essential to life? | 25 |
| which 4 essential elements make up 96% of living matter? | Carbon, oxygen, hydrogen, and nitrogen |
| which elements account for the remaining 4% of an organism's weight? | Phosphorus, sulfur, calcium, potassium, and a few other elements |
| What are two examples of trace elements? | Iron and Iodine |
| Which type of subatomic particle has the smallest mass? | electron |
| The ___ ___ is written as a subscript to the left of the element's symbol | Atomic number |
| The ___ ___ is written as a superscript to the left of an element's symbol | mass number |
| What are some useful applications of radioactive isotopes in biology? | Dating fossils; tracers to follow atoms through metabolism; diagnostic tools in medicine. |
| Water in a reservoir on a hill contains high __ energy. | Potential |
| T F When an electron gains energy, it moves to a shell closer to the nucleus | False. It moves to a shell farther out from the nucleus |
| In the periodic table, the electrons are arranged in rows corresponding to the number of _ _ in their atoms. | Electron shells |
| The _ shell contains the lowest amount of potential energy. | First |
| The chemical behavior of an atom depends mostly on the number of electrons in its _ shell. | Valence/outermost |
| The _ shell contains 4 orbitals, one large spherical s orbital and 3 dumbbell shaped p orbitals | Second |
| No more than _ electrons can occupy a single orbital. | 2 |
| Why is molecular shape crucial in biology? | Because it determines how biological molecules recognize and respond to one another with specificity. |
| What is one factor that affects the rate of a reaction? | The concentration of reactants |
Created by:
Littlebird
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