Exam 1 Flashcards
element
a substance that cannot be broken down to other substances by chemical reactions; elements are the basic building blocks or the “legos”
What are life’s major elements?
oxygen, carbon, hydrogen, and nitrogen; CHON
oxygen
required for cellular respiration; present in most organic compounds; component of water
carbon
forms the backbone of organic molecules; each carbon atom can form four bonds with other atoms
hydrogen
present in most organic compounds; component of water; hydrogen ion (H+) is involved in some energy transfers
nitrogen
component of proteins and nucleic acids; component of chlorophyll in plants
calcium
structural component of bones and teeth; calcium ion (Ca^2+) is important in muscle contraction, conduction of nerve impulses, and blood clotting; associated with plant cell wall
phosphorus
component of nucleic acids and phospholipids in membranes; important in energy transfer reactions; structural component of bone
potassium
potassium ion (K+) is a principle positive ion (cation) in interstitial (tissue) fluid of animals; important in fluid balance; important in nerve function; affects muscle contraction; controls opening of stomata in plants
sulfur
component of most proteins
sodium
sodium ion (Na+) is a principle positive ion (cation) in interstitial (tissue) fluid of animals; important in fluid balance; essential for conduction of nerve impulses; important in photosynthesis in plants
magnesium
needed in blood and other tissues of animals; activates many enzymes; component of chlorophyll in plants
chlorine
chloride ion (Cl-) is principal negative ion (anion) in interstitial (tissue) fluid of animals; important in water balance; essential for photosynthesis
iron
component of hemoglobin in animals; activates certain enzymes
atom
an atom is the smallest unit of matter that still retains the properties of an element; smallest form of organization
subatomical particles
atoms consist of even smaller units called subatomical particles; subatomic particles=protons, neutrons, and electrons
electron
each electron has one unit of negative charge; a subatomic particle; mass=about 1/1800 that of a neutron or proton
proton
each proton has one unit of positive charge; a subatomic particle; mass=about 1 dalton; found in the atomic nucleus
neutron
electrically neutral subatomic particles; mass=about 1 dalton; found in the atomic nucleus
atomic number
number of protons in an element; unless otherwise indicated, atoms have equal numbers of protons and electrons
mass number
the sum of the number of protons and neutrons in the nucleus of an atom; protons + neutrons = mass number
atomic weight
a measure of an atom’s mass; can be approximated by the mass number
isotope
different form of a particular element–the number of neutrons is different; isotopes of an element have the same number of protons and electrons but vary in the number of neutrons
energy levels/electron shells
the different states of potential energy that the electrons of an atom can have; the first shell, closest to the nucleus, has the lowest potential energy; electrons in outer shells have more potential energy; electrons can only change their position if they absorb or release a quantity of energy that matches the difference in potential energy between the two levels
valence electrons
the most energetic electrons; found in the outermost electron shell
valence shell
the outermost electron shell; has higher energy levels than ones closer to the nucleus; atoms with full valence shells, such as noble gases, are very stable since their valence shell is full they don’t look to share/gain/lose electrons
1st electron shell
1s shell; can hold 2 electrons
orbital
space where electrons are found
2nd electron shell
can hold up to 8 electrons; after the first shell, which only holds 2 electrons, the rest hold up to 8 electrons
How is the chemical behavior of an atom determined?
the chemical behavior of an atom is determined by its electron configuration–the distribution of electrons in its electron shells
electron configuration
the distribution of electrons in an atom’s electron shells
When is an atom the most likely to lost, gain, or share electrons?
when it’s valence shell is not full because it wants to fill the shell
covalent bond
a bond formed when atoms share electrons to fill their valence shells; a single covalent bond forms when one pair of electrons is shared, a double covalent bond is formed when two pairs of electrons are shared; a covalent bond is denoted by a dashed line, ex: H-H
covalent compound
atoms linked by covalent bonds form a covalent compound
electronegativity
the attraction of an atom for electrons is called its electronegativity; on the periodic table, increasing electronegativity is to the top and to the right
nonpolar covalent bond
if electrons in a covalent bond are shared equally; so, neither atoms are pulling more on the electrons in the covalent bond due to a higher electronegativity
polar covalent bond
if the electrons in a covalent bond are not shared equally by the two atoms, then this is a polar covalent bond; so, one of the two atoms sharing the electron has a higher electronegativity and therefore pulls on the electron more
How is the shape of a molecule determined?
the shape of a molecule is determined by the arrangement of electron orbitals that are shared by the atoms involved in the bond
ion
a particle with an electric charge; atoms can gain or lose electrons to become an ion
cations
atoms with positive charges
anions
atoms with negative charges
ionic bond
forms when opposite charges attract; forms as a consequence of the attraction between the positive charge of a cation and the negative charge of an anion
oxidation
loss of one or more electrons; OIL RIG–oxidation is losing, reduction is gaining; the goal is to fill the valence shell of the atom
reduction
gain of one or more electrons; OIL RIG–oxidation is losing, reduction is gaining; the goal is to fill the valence shell of the atom
solvents vs solute
solVents will dissolVe other things
hydrogen bond
a weak attractive force that exists between a hydrogen atom with a partial positive charge and an electronegative atom (usually oxygen or nitrogen) with a partial negative charge; these bonds are relatively weak on their own, but are collectively strong when presented in large numbers
compound
when atoms of DIFFERENT elements combine, the result is a chemical compound; consists of two or more different elements combined in a fixed ratio; example: water has a 2:1 ratio of H to O; not all compounds are molecules
molecule
the smallest particle of a covalently bonded element or compound; two or more atoms joined by covalent bonds; molecules are characterized by covalent bonds; not all compounds are molecules
characteristics of water
water is essential to life on earth, in fact we are 70% water; water can have extensive hydrogen bonding; characteristics of water include: cohesion, adhesion, surface tension, kinetic energy, capillary action, heat of vaporization, high specific heat, and evaporative cooling
hydrophilic
substances that have an affinity for water are hydrophilic; “water-loving” substances; these substances contain ionic or polar bonds; ex: salt, sugar
hydrophobic
hydrophobic substances do not mix with water; “water-fearing” substances; contain nonpolar bonds; ex: oil
cohesion
property of water; the property of sticking together–water molecules have a strong tendency to stick to one another because of the hydrogen bonds among the molecules
adhesion
property of water; the ability to stick to many other kinds of substances, most notable those with charged groups of atoms or molecules on their surfaces; these adhesive forces explain how water makes things wet
surface tension
property of water; water has a high degree of surface tension because of the cohesion of its molecules which have a much greater attraction for one another than for molecules in the air, thus, water molecules at the surface crowd together and produce a strong layer as they are pulled downward by the attraction of other water molecules beneath them
kinetic energy (high or low?)
property of water; kinetic energy is the energy of motion; ???
capillary action
the tendency of water to move in narrow tubes, even against the force of gravity; a combination of adhesive and cohesive forces accounts for this
heat of vaporization
water has a high heat of vaporization because its molecules are held together by hydrogen bonds; as a sample of water is heated, some molecules are moving much faster than others (they have more heat), these faster-moving molecules are more likely to escape the liquid phase and enter the vapor phase, when they do, they take their heat with them, lowering the temperature of the sample, a process called evaporative cooling
high specific heat
the amount of energy required to raise the temperature of water is quite large
evaporative cooling
as a sample of water is heated, some molecules are moving much faster than others (they have more heat), these faster-moving molecules are more likely to escape the liquid phase and enter the vapor phase, when they do, they take their heat with them, lowering the temperature of the sample, a process called evaporative cooling
How does water maintain a steady temperature?
a lot of the heat that goes in is used to break hydrogen bonds rather than the result being molecules moving faster and the temperature increasing
pH
The negative logarithm of the hydrogen ion concentration of a solution (expressed as moles per liter). Neutral pH is 7, values less than 7 are acidic, and those greater than 7 are basic; each number you go up is 10 times more acidic, so if you go up two numbers it’s 100x more; looking at the scale, going downwards is increasing alkalinity (more basic) and upwards is increasing acidity (more acidic)
Why is water vital for life on earth?
because it has a high specific heat which means that it keeps our bodies at a relatively stable temperature rather than us overheating
pH and acidity/alkalinity***
a neutral solution (pH 7) has equal concentrations of H+ and OH-; acidic solutions, which have a higher concentration of H+ than OH-, have pH values less than 7; pH values greater than 7 characterize basic solutions, which have an excess of OH-
buffer
a substance or combination of substances that resists changes in pH when an acid or base is added
acidic solution
has a hydrogen ion concentration (H+) that is higher than its hydroxide ion concentration (OH-) and has a pH value of less than 7
basic solution
has a hydrogen ion concentration (H+) that is lower than its hydroxide ion concentration (OH-) and has a pH greater than 7
solute
a dissolved substance is referred to as a solute
solvent
something capable of dissolving many substances, particularly those that are polar or ionic, because of the polarity of water molecules
van der Waals interactions
Weak attractive forces between atoms; caused by interactions among fluctuating charges; operate over very short distances and are weaker and less specific than the other types of interactions we discussed; they are most important when they occur in large numbers and when the shapes of the molecules permit close contact between atoms; although a single interaction is very weak, the binding force of a large number of these interactions working together can be significant
redox reaction
The chemical reaction in which one or more electrons are transferred from one substance (the substance that becomes oxidized) to another (the substance that becomes reduced); oxidation and reduction always occur together
ionic compound
a substance consisting of anions and cations bonded by their opposite charges
polar molecule
molecule that has one end with a partial positive charge and the other with a partial negative charge; polar molecules are generally soluble in water
nonpolar molecule
Molecule that does not have a positively charged end and a negatively charged end; nonpolar molecules are generally insoluble in water
orbital hybridization
when an atom forms covalent bonds with other atoms, the orbitals in the valence shell may become rearranged in a process known as orbital hybridization, thereby affecting the shape of the resulting molecule
orbital
Region in which electrons occur in an atom or molecule
atomic nucleus
clustered together, protons and neutrons compose the atomic nucleus
radioisotopes
Unstable isotopes that spontaneously emit radiation when they decay
chemical formula
A representation of the composition of a compound; the elements are indicated by chemical symbols with subscripts to indicate their ratios; example on pg 31
simplest formula
A type of chemical formula that gives the smallest whole–number ratio of the component atoms; example on pg 31
molecular formula
The type of chemical formula that gives the actual numbers of each type of atom in a molecule; example on pg 31
structural formula
A type of chemical formula that shows the spatial arrangement of the atoms in a molecule; example on pg 31