Chapter 2 the chemical context of life Flashcards
The atomic number is the number of ____ in an element
protons
The mass number is the ___ in an element. The number of neutrons can be determined by ___
total number of protons and neutrons in an atom
Mass number- Atomic mass= Neutrons
Isotopes differ by the number of ___ in each isotope
neutrons
How do radioactive tracers function?
Radioactive isotopes are incorporated into biologically active molecules, which then track atom’s metabolism
How does radiometric dating work?
A parent isotope decays into a daughter isotope at a rate known as a “half-life.”
Scientists measure the ratio of different isotopes and calculate how many half-lives have passed since an organism was fossilized.
True or False, the third shell has the highest level of potential energy in an atom, while the first shell has the lowest
True. The further away from the nucleus, the more energy is absorbed.
What is an orbital?
3D space where an electron is found most of the time
How many electrons can occupy a single orbital?
two
What are Van der Waals interactions?
Electrons are not always evenly distributed; at any instant, they may accumulate by chance in one part of a molecule or another. The results are ever changing regions of positive and negative charge that enable all atoms and molecules to stick to one another
Individually weak and occur only when atoms and molecules are very close together. When many such interactions occur simultaneously, however, they can be powerful
Compared with 31 P, the radioactive isotope 32 P has
(A) a different atomic number.
(B) one more proton.
(C) one more electron.
(D) one more neutron
(D) one more neutron
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 element is very rare on Earth.
(D) the element enhances health but is not essential for the
organism’s long-term survival.
(B) the element can be used as a label to trace atoms through an organism’s metabolism.
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.
(B) the existence of unpaired electrons in the valence shell.
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.
(A) The atom has more electrons than protons.
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 are equal.
(D) The rates of the forward and reverse reactions are equal.
