[2] Practice Test Flashcards
There are __________ naturally occurring elements.
92
Which of the following is a trace element?
[A] nitrogen
[B] copper
[C] carbon
[D] oxygen
[E] hydrogen
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, making up 96%?
hydrogen, oxygen, nitrogen, carbon
If I added proton number and neutron number, what would be the result?
atomic mass number
Which of the subatomic particles, as its name implies, is electrically neutral?
neutrons
The number of protons in an uncharged atom __________.
equal the number of electrons
Consider a hypothetical atom with an atomic number of 4 and an atomic mass of 9.0. How many neutrons does this atom have?
5
An uncharged atom of nitrogen (atomic number = 7) has __________.
seven protons, and seven electrons
Isotopes of an element will always differ in __________.
atomic mass
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 neutrons
6 protons
6 electrons
Phosphorus-32 (radioactive) has __________ than phosphorus-35 (normal).
three fewer neutrons
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
Radioactive isotopes are useful in scientific research because __________.
they can be used as tracers to follow particular atoms and molecules through metabolic pathways, especially in medicine
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
The chemical characteristics or reactivity of an element depend mostly on the __________.
number of electrons in its outermost shell
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)?
6
For most atoms, a stable configuration of electrons is attained when the atom __________.
has a full number 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
When one or more pairs of valence electrons are shared by two neutral atoms, what type of bond is formed?
a covalent bond
A polar covalent bond is a bond that __________.
the electrons of the bond are not shared equally
A covalent bond is likely to be polar if __________.
one of the atoms sharing electrons is much more electronegative
When two atoms are so unequal in their attraction for valence electrons that the more electronegative atom strips an electron completely away from its partner, the two resulting oppositely charged atoms (or molecules)____________.
are ions
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?
11
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?
-2
Ionic bonds form as a result of __________.
attraction between ions that have opposite charges