Chapter 2 Flashcards
(19 cards)
Atoms of a specific element always have a constant number of _____.
protons
isotopes
neutrons
electrons
protons
Which four elements make up 96 percent of matter found in living organisms?
hydrogen, carbon, oxygen, sulfur
hydrogen, carbon, oxygen, nitrogen
carbon, sulfur, nitrogen, iron
sulfur, hydrogen, oxygen, nitrogen
hydrogen, carbon, oxygen, nitrogen
What is the difference between 12C and 13C?
12C can form four covalent bonds and 13C only forms three
12C always forms nonpolar covalent bonds with hydrogen, whereas 13C forms polar covalent bonds.
12C has one less neutron than 13C
12C has one less proton than 13C.
12C has one less neutron than 13C
An element in the second row of the periodic table that has four valence electrons would most likely _____.
be more electronegative than an element with six valence electrons in the same row of the periodic table
form four covalent bonds
form ionic bonds
have a full outer shell and be unreactive
form four covalent bonds
Which of the following is necessary for an atom to participate in the formation of a double covalent bond?
The participating atoms must have two or more valence electrons.
There has to be a difference in electronegativity between it and the atom with which it forms the double covalent bond.
The participating atoms must have two or more unpaired electrons.
The participating atoms must have a full outer shell.
The participating atoms must have two or more unpaired electrons.
The electron-sharing continuum represents the degree to which electrons are shared in chemical bonds by showing that _____.
atoms with no charge transfer electrons with atoms with full charge
atoms with partial charges form nonpolar covalent bonds and share electrons equally
atoms with full charges transfer electrons and form ionic bonds
atoms with full charge form nonpolar covalent bonds and share electrons equally
atoms with full charges transfer electrons and form ionic bonds
Unlike an anion, a cation has a(n) _____.
negative charge
positive charge
electric charge
neutral charge
positive charge
Which of the following best describes why ionic molecules dissolve and dissociate in water?
Water is liquid at room temperature.
Water is a polar, covalently bonded substance.
Water is hydrophobic.
Water is formed from nonpolar covalent bonds between oxygen and hydrogen.
Water is a polar, covalently bonded substance.
Water has a high capacity for energy absorption, surface tension, and functioning effectively as a solvent for polar covalently bonded and ionically bonded molecules. What feature of water imparts these properties?
The hydrogen and oxygen that make up water form nonpolar covalent bonds.
It readily dissociates to form H+and OH¯ ions.
Water readily forms hydrogen bonds with other water molecules, and with polar solutes.
It has a high molecular weight.
Water readily forms hydrogen bonds with other water molecules, and with polar solutes.
An acid is defined by which of the following?
It is insoluble in water.
It has a high pH value.
It donates protons to other substances in a solution.
It accepts protons from other elements in a solution.
It donates protons to other substances in a solution.
What is the significance of buffers in biological systems?
They are usually involved in chemical reactions that result in energy production.
They help maintain homeostasis with respect to pH.
They are not present and are therefore insignificant in biological systems.
They help maintain a constant temperature in biological systems.
They help maintain homeostasis with respect to pH.
As an example of a(n) _____, household bleach can be characterized as having a _____.
neutral solution; pH of 7
base; pH greater than 7
base; pH less than 7
acid; proton concentration larger than 1 x 10-7 M
base; pH greater than 7
In the chemical equation for burning methane (CH4 + O2 → CO2 + H2O), CH4 and O2 are the _____ and CO2 and H2O are the _____.
anions; cations
products; reactants
reactants; products
molecules; atoms
reactants; products
A large boulder is balanced on top of a hill. You give the boulder a push, and it rolls down the hill. This is an example of converting _____ energy to _____ energy.
kinetic; thermal
potential; kinetic
kinetic; potential
chemical; kinetic
potential; kinetic
An iceberg near the Arctic Circle represents which unusual property of water?
its higher density as a liquid than as a solid
its heat of vaporization
its effectiveness as a solvent
its high specific heat
its higher density as a liquid than as a solid
Which factor most accurately defines whether or not a chemical reaction is spontaneous?
pH of reactants or products
degree of entropy (disorder in a group of molecules)
temperature of products and reactants
difference in energy level between products and reactants
difference in energy level between products and reactants
Why do high temperatures speed chemical reactions?
Heat increases the concentration of reactants.
Heat causes the reactants to move faster and collide more often.
Heat makes reactions spontaneous.
Heat increases the rate of reactant formation in a spontaneous reaction.
Heat causes the reactants to move faster and collide more often.
An organic molecule always contains one or more atoms of _____.
sulfur
nitrogen
carbon
oxygen
carbon
Which of the following groupings of atoms determines molecular properties and the types of chemical reactions in which a molecule participates?
carbon skeleton
functional group
hydrogen atoms
hydrogen ion concentration
functional group
