Bio 235 Chapter 2 Questions And Answers With Verified Solutions

Major elements - Answer-• Oxygen O • Carbon C • Hydrogen H • Nitrogen N (96% or body mass) Chemical element - Answer-The building blocks of all forms of matter (living and nonliving) Chemical symbol - Answer-one or two letters of the element's name in English, latin, or another language. Lesser Elements - Answer-Make up 3.6% of total body mass. Calcium, phosphorus, potassium, sulfur, sodium, chlorine, magnesium and iron Trace elements - Answer-Account for about 0.4% of total body mass. There are 14 trace elements. Include aluminium, boron, chromium, cobalt, copper, fluorine, iodine, manganese, molybdenum, selenium, silicon, tin, vanadium, and zinc. Atom - Answer-The smallest units of matter that retain the properties and characteristics of the element. subatomic particles - Answer-Atoms are made up of dozens of subatomic particles. Most important are protons, neutrons, and electrons. Proton - Answer-A subatomic particle that has a positive charge and that is found in the nucleus of an atom Neutron - Answer-A subatomic particle that has no charge and that is found in the nucleus of an atomElectron - Answer-A subatomic particle that has a negative charge that move about in the large space surrounding the nucleus. electron shells - Answer-Depicted as simple circles around nucleus; each shell holds differing numbers of electrons atomic number - Answer-the number of protons in the nucleus of an atom mass number - Answer-the sum of the protons and neutrons in an atom isotopes - Answer-atoms of an element that have the same number of protons but different number of neutrons (and thus diff mass number) atomic mass/weight - Answer-average mass of all naturally occurring isotopes of that element Ion - Answer-an atom that has a positive or negative charge because it has unequal number of protons and electrons ionization - Answer-the process of giving up or gaining electrons molecule - Answer-when two or more atoms share electrons compound - Answer-a substance that contains atoms of two or more different elements free radical - Answer-an atom or group of atoms with an unpaired electron in the outermost shell Chemical bonds - Answer-the forces that hold together the atoms of a molecule or a compound Valence shell - Answer-the outermost shell of an atom (8 electrons= chemically stable)How are ionic bonds formed? - Answer-one atom gives up an electron to a second atom Cation - Answer-A positively charged ion Anion - Answer-A negatively charged ion Electrolyte - Answer-An ionic compound that breaks apart into positive and negative ions in a solution How are covalent bonds formed? - Answer-Atoms form a covalently bonded molecule by sharing one, two, or three pairs of valence electrons Single covalent bond - Answer-when two atoms share one electron pair Double covalent bond - Answer-when two atoms share two pairs of elctrons triple covalent bond - Answer-when two atoms share three pairs of electrons. the larger the number of shared electrons, the stronger the bond. nonpolar covalent bond - Answer-two atoms share the electons equally. always the case between two identical atoms. polar covalent bond - Answer-when the sharing of electrons between two atoms is unequal- the nucleus of one atom attracts the shared electrons more strongly that the nucleus of the other atom electronegativity - Answer-the power to attract electrons to itself