Exam 1 Material (Gen. Biology – Intro to the Cell)
BASIC CHEMISTRY:
Which elements make up 96% of living matter?
Hydrogen, Oxygen, Nitrogen, and Carbon
What are Protons, Neutrons, and Electrons?
PROTON: a subatomic particle with a single positive electrical charge with a mass of about 1.7 ×10−24 g
(or 1 Dalton), and is found in the nucleus of an atom.
NEUTRON: a subatomic particle having no electrical charge (electrically neutral), with a mass of about
−24
1.7 ×10 g (or 1 Dalton), and is found in the nucleus of an atom.
1
ELECTRON: a subatomic particle with a single negative electrical charge and a mass about that of
2,000
a neutron or proton (or 1/2000 Dalton). One or more electrons move around the nucleus of an atom.
What is an element’s atomic number, atomic mass, and mass number?
ATOMIC NUMBER: indicates how many PROTONS are in its nucleus.
MASS NUMBER: the sum of PROTONS + NEUTRONS in its’ nucleus.
ATOMIC MASS: equivalent to the mass number, an approximation of the total mass of the atom.
What are isotopes? What is the difference between stable isotopes and a radioactive isotope? How can each be
used in research?
ISOTOPES: Isotopes are different forms of the same element. They have the same number of PROTONS
but a different number of NEUTRONS.
STABLE ISOTOPES: Isotopes whose nuclei do not have a tendency to lose subatomic particles
RADIOACTIVE ISOTOPES: an isotope (an atomic form of a chemical element) that is unstable; the
nucleus decays spontaneously, giving off detectable particles and energy.
What is an electron shell? How many electrons can each of the first three shells hold? What is the difference
between a shell and an orbital?
ELECTRON SHELL: an energy level of electrons at a characteristic average distance from the nucleus of
an atom.
ORBITAL: the three-dimensional space where an electron is found 90% of the time.
What is a valence shell? How do you figure out how many electrons are in an atom’s valence shell?
VALENCE SHELL: the number of electrons in the outermost shell of an atom that effects the chemical
behavior of an atom.
VALENCE ELECTRONS: electrons in the valence shell
What are the different types of bonds and what is the difference between them?
COVALENT BOND: when two atoms share one or more pairs of valence electrons
POLAR COVALENT BOND: the result of unequal sharing of electrons
EXAMPLE
.
1
, A covalent bond between atoms that differ in electronegativity. The shared electrons are
pulled closer to the more electronegative atom, making it slightly negative, and the other atom
slightly positive.
NONPOLAR COVALENT BOND: a type of covalent bond in which electrons are shared equally
between two atoms of similar electronegativity.
EXAMPLE
IONIC BOND: a bond formed between oppositely charged ions. (Ions are atoms that have gained or lost
one or more electrons, thus acquiring a charge).
CATION: a positively charged ion
ANION: a negatively charged ion
IONIC BOND DIAGRAM
HYDROGEN BOND: a weak chemical bond between a hydrogen atom and an electronegative atom on a
different molecule.
HYDROGEN BOND DIAGRAM/EXAMPLE
VAN DER WAALS INTERACTIONS: weak forces that result when electrons, by chance, become unevenly
distributed, forming regions of positive and negative charges, allowing atoms and molecules to stick to
each other.
VAN DER WAALS INTERACTION DIAGRAM/EXAMPLE
2
BASIC CHEMISTRY:
Which elements make up 96% of living matter?
Hydrogen, Oxygen, Nitrogen, and Carbon
What are Protons, Neutrons, and Electrons?
PROTON: a subatomic particle with a single positive electrical charge with a mass of about 1.7 ×10−24 g
(or 1 Dalton), and is found in the nucleus of an atom.
NEUTRON: a subatomic particle having no electrical charge (electrically neutral), with a mass of about
−24
1.7 ×10 g (or 1 Dalton), and is found in the nucleus of an atom.
1
ELECTRON: a subatomic particle with a single negative electrical charge and a mass about that of
2,000
a neutron or proton (or 1/2000 Dalton). One or more electrons move around the nucleus of an atom.
What is an element’s atomic number, atomic mass, and mass number?
ATOMIC NUMBER: indicates how many PROTONS are in its nucleus.
MASS NUMBER: the sum of PROTONS + NEUTRONS in its’ nucleus.
ATOMIC MASS: equivalent to the mass number, an approximation of the total mass of the atom.
What are isotopes? What is the difference between stable isotopes and a radioactive isotope? How can each be
used in research?
ISOTOPES: Isotopes are different forms of the same element. They have the same number of PROTONS
but a different number of NEUTRONS.
STABLE ISOTOPES: Isotopes whose nuclei do not have a tendency to lose subatomic particles
RADIOACTIVE ISOTOPES: an isotope (an atomic form of a chemical element) that is unstable; the
nucleus decays spontaneously, giving off detectable particles and energy.
What is an electron shell? How many electrons can each of the first three shells hold? What is the difference
between a shell and an orbital?
ELECTRON SHELL: an energy level of electrons at a characteristic average distance from the nucleus of
an atom.
ORBITAL: the three-dimensional space where an electron is found 90% of the time.
What is a valence shell? How do you figure out how many electrons are in an atom’s valence shell?
VALENCE SHELL: the number of electrons in the outermost shell of an atom that effects the chemical
behavior of an atom.
VALENCE ELECTRONS: electrons in the valence shell
What are the different types of bonds and what is the difference between them?
COVALENT BOND: when two atoms share one or more pairs of valence electrons
POLAR COVALENT BOND: the result of unequal sharing of electrons
EXAMPLE
.
1
, A covalent bond between atoms that differ in electronegativity. The shared electrons are
pulled closer to the more electronegative atom, making it slightly negative, and the other atom
slightly positive.
NONPOLAR COVALENT BOND: a type of covalent bond in which electrons are shared equally
between two atoms of similar electronegativity.
EXAMPLE
IONIC BOND: a bond formed between oppositely charged ions. (Ions are atoms that have gained or lost
one or more electrons, thus acquiring a charge).
CATION: a positively charged ion
ANION: a negatively charged ion
IONIC BOND DIAGRAM
HYDROGEN BOND: a weak chemical bond between a hydrogen atom and an electronegative atom on a
different molecule.
HYDROGEN BOND DIAGRAM/EXAMPLE
VAN DER WAALS INTERACTIONS: weak forces that result when electrons, by chance, become unevenly
distributed, forming regions of positive and negative charges, allowing atoms and molecules to stick to
each other.
VAN DER WAALS INTERACTION DIAGRAM/EXAMPLE
2
