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37 Cards in this Set

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  • Back
Evaluate the following statement: Oxygen is not a greenhouse gas; therefore, gases containing oxygen, such as ozone, nitrous oxide, and carbon dioxide, are not greenhouse gases either
Emergent properties of compounds are more than simply the sum of their parts.
There are _____ naturally occurring elements
There are 92 naturally occurring elements, and about 25 of these are essential to life.
What is an example of a trace element?
Copper (Cu) is a trace element. Copper accounts for less than 0.01% of living matter.
What are the four most abundant elements found in living systems?
hydrogen, oxygen, nitrogen, and carbon
These four elements make up about 96% of living matter
Which of the following has negligible mass?
electron, because the mass of an electron is only about 1/2,000 that of a proton or neutron, electrons are not considered when computing atomic mass.
Which of the following subatomic particles has appreciable mass and lacks a charge?
neutron, A neutron weighs about 1.7 x 10-24 grams (has a mass close to 1 dalton), and it is electrically neutral.
The number of protons in an uncharged atom _____.
equals the number of electrons

(The number of neutrons determines the isotope, not the number of protons. For example, the different isotopes of an element would have different numbers of neutrons, but each of the different isotopes would have the same number of protons and electrons.)
Consider a hypothetical atom with an atomic number of 4 and a net electronic charge of +1. How many neutrons does this atom have?
The answer cannot be determined from the information provided.
All the atoms of an element have the same number of protons, but some atoms have different numbers of neutrons than other atoms of the same element; therefore, the atoms have different mass numbers. Without the mass number (number of protons + neutrons), it is not possible to determine the number of neutrons.
An uncharged atom of nitrogen (atomic number = 7) has _____.
seven protons and seven electrons
Isotopes of an element will always differ in _____.
atomic mass
Atomic mass refers to the number of protons and neutrons in an atom. Atomic forms of an element with the same number of protons (atomic number) but different numbers of neutrons are isotopes of that element.
A particular carbon isotope has an atomic number of 6 and an atomic mass of 14. The respective number of neutrons, protons, and electrons that this carbon isotope has is _____.
8, 6, and 6
The atomic number, 6, is equal to the number of protons. Therefore, the number of electrons in an electrically neutral atom would also be 6. The number of neutrons must be 8 because the atomic mass is 14 (14 - 6 = 8).
The most common form of calcium has 20 protons, 20 neutrons, and 20 electrons. Which of the following elements would be an isotope of calcium?
an atom with 20 protons, 21 neutrons, and 20 electrons
Phosphorus-32 (radioactive) has _____ than phosphorus-35 (normal).
three fewer neutrons
The numbers 32 and 35 refer to mass number (number of protons plus neutrons). All the atoms of the same element have the same number of protons, but different isotopes of the same element have different numbers of neutrons. Because 35 - 32 = 3, P-32 has three fewer neutrons than P-35.
Radioactive isotopes are useful in scientific research because _____.
they can be used as tracers to follow particular atoms and molecules through metabolic pathways.
Because they are detectable in very small amounts, a few labeled molecules can be traced through an organism's body to see how they are used.
Potassium (atomic number 19, mass number 40) and sodium (atomic number 11, mass number 23) have similar chemical properties and reactive behavior. This is because uncharged atoms of potassium and sodium _____.
have different mass numbers and each has one electron in its outermost electron shell
Although potassium has 19 electrons and sodium has 11 electrons, each has only one electron in its outermost electron shell.
The chemical characteristics or reactivity of an element depend mostly on the _____.
number of electrons in its outermost shell
Only electrons are directly involved in the interactions between atoms, and the number of electrons in the outermost shell determines the chemical behavior or reactivity of an atom.
Some groups of elements react chemically in similar ways. For example, the chemistry of sodium and the chemistry of lithium are similar. The chemistry of chlorine and the chemistry of iodine are also similar. These similarities in chemistry result when different elements have similar _____.
numbers of outer-shell electrons
How many electrons would be present in the valence shell of a sulfur atom (atomic number 16, mass number 32)?
six electrons
For most atoms, a stable configuration of electrons is attained when the atom _____.
has eight electrons in its outermost shell
An atom that normally has _____ in its outer shell would not tend to form chemical bonds with other atoms.
eight electrons
Eight electrons will leave no unpaired electrons in the valence shell. In this configuration atoms are chemically unreactive or inert.
A sodium atom has a mass number of 23. Its atomic number is 11. How many electrons does it have if it is not an ion?
The number of electrons will equal the number of protons in an electrically neutral atom.
When the proton number and electron number are unequal, the atom or molecule _____.
is an ion
When the proton number and electron number are unequal, the atom or molecule has a net positive (cation) or negative charge (anion).
A covalent bond is likely to be polar if _____.
one of the atoms sharing electrons is much more electronegative
A polar covalent bond is a bond that _____.
has shared electrons pulled closer to the more electronegative atom

Polar covalent bonds share electrons unequally, so that one part of the molecule has a partial negative region and one part a partial positive region.
When one or more pairs of valence electrons are shared by two neutral atoms, what type of bond is formed?
a covalent bond
Covalent bonds are formed between atoms that share one or more pairs of valence electrons.
Copper has an atomic number of 29 and a mass number of 64. What would result if an uncharged copper atom lost two electrons?
The atomic number would remain 29, the mass number would remain 64, and the atom would be a cation with a +2 charge.
The compound CaSO4 ionizes into a calcium ion and a sulfate ion (SO4). Calcium has two electrons in its outer shell. Upon ionization, what would you expect the charge on the sulfate ion to be?
Ionic bonds form as a result of _____.
attraction between ions that have opposite charges
Oppositely charged ions attract each other electrically, forming an ionic bond.
A hydrogen bond _____.
is a weak chemical bond
-In a hydrogen bond the hydrogen has a partial positive charge.
What is the role of van der Waals interactions in biological molecules?
Although they are weak bonds, van der Waals interactions help to reinforce the three-dimensional shapes of large molecules.
What is an example of a molecule that has the shape of a completed tetrahedron?
methane (CH4)
-Molecules containing multiple carbon atoms have more complex overall shapes. (so it couldn't be glucose C6H12O6)
Pharmaceutical researchers are often interested in blocking particular receptor proteins on cell surfaces. What chemical property of a molecule would be most important for this type of application?
the molecule's shape
A statement true about chemical reactions?
They involve the making and breaking of chemical bonds.
Describe a reversible reaction that has reached chemical equilibrium?
The rate of the reverse reaction equals the rate of the forward reaction.
Cells are surrounded by water, and cells themselves consist of about 70 to 95% water. As a result, _____.
Water is a polar molecule. This means that _____.
the opposite ends of the molecule have opposite electrical charges
When equally electronegative atoms bond, the electrons are shared equally between them, forming a nonpolar bond.
The partial charges on a water molecule occur because of _____.
the unequal sharing of electrons between the hydrogen and the oxygen atoms of a water molecule