Lecture 3 Flashcards
What is an electron orbital?
a 3D space where an electron is found 90% of the time
How many electrons can occupy each orbital?
2
What is the definition of energy?
the capacity to cause change
What is potential energy?
the energy that matter has because of its location or structure
How do the electrons in an atom differ?
By their amount of potential energy
What is an electrons state of potential energy called?
energy level or electron shell
What are valence electrons?
electrons in the outermost shell (valence shell)
What influences the chemical behavior of an element?
valence electrons
How do electrons close to the nucleus behave?
they tend to stay there and they are typically hard to lose (oxidze)
What does it mean for something to oxidize?
It loses electrons
What does it mean for an element to be inert?
It has a full valence shell
What effect do unpaired electrons have on an atom?
They make atoms more reactive
How is the chemical behavior of an atom determined?
By the distribution of electrons in the electron shell
What type of bond holds together shared valence electrons with other atoms?
Chemical bonds
What are the types of covalent bonds?
polar and nonpolar
What are the types of noncovalent bonds?
Ionic, hydrogen bonds, Van der Waals, Hydrophobic interactions (not really a bond)
What is a covalent bond?
The sharing of a pair of valence electrons by two atoms
Describe the strength of covalent bonds.
strong and contain stored energy
What is a nonpolar covalent bond?
atoms share the electron equally
What is a polar covalent bond?
one atom is more electronegative, and the atoms do not share the electron equally
What does unequal sharing of electrons result in?
a partial charge for each atom or molecule
What is electronegativity?
an atoms attraction for the electrons in a covalent bond
How does electronegativity affect an atom?
The more electronegative an atom is, the more strongly it pulls shared electrons toward itself
What bond form most cell molecules?
covalent
How are large biological molecules held together?
by weak bonds
What is one advantage of weak bonds?
Their reversibility
What is an ionic bond?
When atoms strip (not share) electrons from their bonding partners
An attraction between an anion and cation
What is an ion?
A charged atom or molecule
What is a cation?
A positively charged ion
What is an anion?
A negatively charged ion
What are compounds called that are formed by ionic bonds?
Ionic compounds or salts (not molecules)
What is a hydrogen bond?
When a hydrogen atom is covalently bonded to one electronegative atom and is also attached to another electronegative atom
What two elements are commonly found with hydrogen bonding?
Oxygen and nitrogen
What is the strength of Van der Waals forces?
Individually weak, collectively strong
What is a hydrophobic interaction?
nonpolar substances that cant hydrogen bond with water
What is the only substance that is common to exist in the natural environment in all three physical states of matter?
water
What is unique to water that helps make Earth suitable for life?
emergent properties
Polar covalent bonds in water molecules result in _____.
hydrogen bonding
What allows water molecules to form hydrogen bonds with eachother?
Polarity
Water is in a permanent ___.
Dipole
What are the four emergent properties of water?
Cohesive behavior and water tension
Ability to moderate temperature
Expansion upon freezing
Versatility and a solvent
What type of things can dissolve in water?
ionic compounds, nonionic polar molecules, large polar molecules (proteins),
What does hydrophilic mean?
affinity for water
What is an acid?
A substance that increases the H+ concentration of a solution
What is a base?
a substance that reduces the H+ concentration of a solution
What do strong acids an bases do in water?
dissociate completely
What do acids and bases shift
OH- and H+ concentrations
What is the internal pH of most living cells?
7
What are buffers?
substances that minimize changes in concentrations of H+ and OH- in a solution
What does a buffer usually consist of?
weak acid and its corresponding base, which combine reversibly with H+ ions
