Intro To Bio (Gilmore-Hesser) 2

compound

contains two or more different elements in a fixed ratio

isotopes

differ from each oter in neutron number and therefore mass. unstable isotopes give off particles and energy as radioactivity

chemical reaction

changes reactants into products while conserving matter

orbitals

electrons exist in orbitals, three dimensional spaces with specific shapes that are components of electron shells

1. in the term trace element, the adjective trace means that a. the element is required in very small amounts b. the element can be used as a label to trace atoms through an organism's metabolism c. the elements is very rare on earth d. the element enhances health but is not essential for the organism's long term survival e. the element passes rapidly through the organism

A

4. which statement is true of all atoms that are anions a. the atom has more electrons than protons b. the atom has more protons than electrons c. the atom has fewer protons than does a neutral atom of the same element d. the atom has more neutrons than protons e. the net charge is 1-

A

3. the reactivity of an atom arises from a. the average distance of the outermost electron shell from the nucleus b. the existence of unpaired electrons in the valence shell c. the sum of the potential energies of all the electron shells d. the potential energy of the valence shell e. the the energy difference between s and p orbitals

B

6. we can represent atoms by listing the umber of protons neutons and electrons for example 2p+,2n^0, 2e-. for helium. which of the following represents the atomic number 18O isotope of oxygen? a. 6p+,8n^0,6e- b. 8p+,10n^0,8e- c. 9p+,9n^0,9e- d. 7p+,2n^0,9e- e. 10p+,8n^0,9e-

B

7. the atomic number of sulfur is 16. sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. based on the number of valence electrons in a sulfur sulfide. based on the number of valence in a sulfur atom predict the molecular formula of the compound

C H2S

5. which of the following statements correctly describes any chemical reaction that has reached equilibrium a. the concentrations of products and reactants are equal b the reaction is now irreversible c both forward and reverse reactions have halted d. the rates of the forward and reverse reactions and equal e. no reactants remain

D

2. compared with atomic number 31 P the radioactive isotopes atomic number 32 P has a. a different atomic number b. a different charge c. more than one proton d. one more electron e. one more neutron

E

hydrogen bonds

an attraction between a hydrogen atom carrying a partial positive charge and an electronegative atom

elements

cannot be broken down chemically to other substances

molecules

consist of 2 or more covalently bonded atoms

what coeficients must be placed in the following blanks that all atoms are accounted for in the product C6H1206-->______C2H60+_____C02

e 2;2

atomic number

electrically neutral atom has equal numbers of electrons and protons; the number of protons determines the atomic number

covalent bonds

form when pairs of electrons are shared

chemical bonds

from when atoms interact and complete their valence shells

the atomic mass

measured in daltons and i roughly the sum of protons plus neutrons

van der waals interaction

occurs between transiently positive and negative regions of olecules

valence shell

outer shell

polar covalent bonds

pulled closer to the more electronegative atm

chemical equilibrium

reached when the forward and reverse reaction rates are equal

electronegativity

the attraction of an atom for the electrons of a covalent bond

electron shells

the electrons in a shell have a characteristic energy level. electron distribution in shells determines the chemical behavior of an atom

atom

the smallest unit of an element has the following components: nucleus, protons, neutrons and electrons