Chemistry/Physiology Recap Flashcards
Chemical energy
- Stored in bonds of chemical substances
- ex. Glucose (C6H12O6)
The energy is stored in the covalent bonds between carbon atoms
Some bacteria require energy in the form of the _______________.These bacteria cannot manufacture food like ___________ nor absorb nutrients from the environment like _________.
- Organic Molecules
- photosynthetic organisms
- fungi
The organic ___________ some bacteria take up are broken down to make _______.
- molecules
- ATP
________ provides the energy cells need to stay alive.
ATP (Adenosine Triphosphate)
_________ in molecules is stored in the ___________between _________ that make up the molecules.
- energy
- bonds
- carbon atoms
definition of chemistry
Chemistry is the study of interactions between atoms and molecules
definition of atom
The atom is the smallest unit of matter and cannot be subdivided into smaller substances
Atoms interact to form ___________.
molecules
Atoms are composed of ____________.
subatomic particles
what are the 3 subatomic particles?
Protons, neutrons, electrons
Protons
positively charged particles found in the nucleus of an atom.
Neutrons
neutrally charged particles found in the nucleus of an atom.
Electrons
negatively charged particles that orbit nucleus in an electron cloud
planetary model of an atom
orbital model
what are the 3 smallest elements?
- hydrogen
- helium
- lithium
- hydrogen (H)
- 1 proton, 0 neutrons, 1 electron
- helium atom (He)
- 2 protons, 2 neutrons, 2 electrons
- lithium atom (Li)
- 3 protons, 4 neutrons, 3 electrons
outer layer of e- is called the ________, and the e- in that layer are called __________.
- valence shell
- valence electrons
Only ___________are involved in ____________between any two atoms.
- valence electrons
- chemical bonding
what are the 4 chemically reactive elements?
- hydrogen
- carbon
- sodium
- oxygen
Most atoms chemically combined with other atoms to form __________________.
molecules and compounds
definition of a molecule
Two or more atoms bonded together (e.g., H2 or C6H12O6)
what is special about valence chemically reactive elements?
- Their valence shell is not full they tend to gain, lose, or share electrons (form bonds) with other atoms to achieve stability
Electrons in valence shell (outermost electron shell); __________________ and ______________
- Have most potential energy
- Are chemically reactive electrons
Octet rule (rule of eights)
Except for the first shell (full with two electrons) atoms interact to have eight electrons in their valence shell
single covalent bond
- one pair of electrons is shared between atoms
- ex. methane gas= CH4
double covalent bond
- two pairs of electrons are shared between atoms
- ex. oxygen gas O2
Triple covalent bond
- Three pairs of electrons are shared between atoms
- ex. Nitrogen gas
When two or more atoms join together to form molecules, the atoms form ____________.
- Chemical bonds that hold them togther
What are the 3 major types of chemical bonds?
- Covalent bonds
- Ionic bonds
- Hyrogen bonds
What are the 2 types of covalent bonds
- polar covalent bonds
- non-polar covalent bonds
Covalent Bonds
- Prefix “co” means “together”, as in cooperate (work together) or cohabitate (live together); “valent” refers to valence e- (in the outermost shell or layer).
- “covalent” means sharing e- pairs together in the valence shell. Keeping in mind the Octet Rule, in which the atoms are trying to make their valence shell “full”, one way to accomplish this is for two atoms to share e- pairs. If one atom shares one e- and the other atom shares another e-, then both atoms have the e- they want to complete their valence shell.
- Covalent bonds - Formed by sharing of two or more valence shell electrons such that each atom fills its valence shell at least part of the time
Non-polar covalent bond
- Electrons shared equally > nonpolar covalent bond
- Produces electrically balanced, nonpolar molecules such as CO2
- charge is balanced among atoms
- Carbon dioxide (CO2) molecules are linear and symmetrical. They are nonpolar
Polar Covalent bond
- Unequal sharing of electrons > polar covalent bond
- Atoms in bond have different electron-attracting abilities
- usually occurs with electronegative elements like oxygen or nitrogen.
- slight negative charge at one end of molecule and slight positive charge at the other end.
Electronegative
- oxygen and nitrogen are electronegative
- Strong electron-attracting ability
- Shares e- unequally with other atoms
- V-shaped water (H2O) molecules have two poles of charge—a slightly more negative oxygen end (d–) and a slightly more positive hydrogen end (d+).
Ionic bond
- complete transfer of electrons
- separate ions (charged particles) form
- ex. Na+ Cl-
- Transfer of valence shell electrons from one atom to another forms ions; Again, the transfer occurs so that both atoms fulfill the Octet Rule. It is easier for Na atoms to give up one e- than to gain 7 e-; similarly, it is easier for Cl to gain 1 e- than to lose 7 e-.
- One becomes an anion (negative charge), an atom that gained one or more electrons; One becomes a cation (positive charge), an atom that lost one or more electrons; Attraction of opposite charges results in an ionic bond
Hydrogen bonds
- Attractive force between hydrogen (usually δ+) of one molecule and an electronegative atom of another molecule or another atom in the same molecule
- Not true bond > no transfer or sharing of e- (but it is an attractive force between atoms)
- Hold individual water molecules together; gives water important properties for life (universal solvent, resistant to temp changes, cohesion and adhesion, evaporative cooling)
- H bonds also hold large molecules in their three-dimensional shape by acting as intramolecular bonds
- The slightly positive ends (d+) of the water molecules become aligned with the slightly negative ends (d–) of other water molecules.
Hydrogen bonds hold individual water molecules together (what kind of bond holds atoms together in a single water molecule?)
Polar covalent bonds
Hydrogen bonds gives water properties which are important for life, what are they?
- universal solvent
- resistant to temperature changes
- cohesion and adhesion
- evaporate cooling
Water is the universal solvent, what does that mean?
- it dissolves MANY substances
- water molecules surround the atoms of the substance being dissolved, forming “hydration spheres” around the atoms or parts of the molecules being dissolved. When forming hydration spheres around atoms, the partially negative O atoms in water molecules will point toward the positively charged atoms of the substance being dissolved (Na+ ions, in this case), and the partially positive H atoms will point toward the negatively charged atoms of the substance being dissolved (Cl- ion, in this case). In many cases, the substance is invisible once dissolved, but you still know it is present in the water (dissolved) because you can taste or smell it.
Chemical reactions
- Chemical reactions occur when chemical bonds are formed, rearranged, or broken.
- Represented as chemical equations using molecular formulas
- Chemical equations contain: Reactants (Number and kind of reacting substances), and Product(s)
Synthesis Reactions
- A + B —-> AB (e.g. 2H2 +O2 —-> 2H2O)
- Atoms or molecules combine to form larger, more complex molecule
- Always involve bond formation (Anabolic)
- reactants come togther to make a product
Decomposition Reactions
- AB ® A + B (e.g. NaCl à Na+ + Cl- )
- Molecule is broken down into smaller molecules or its constituent atoms
- Reverse of synthesis reactions
- Involve breaking of bonds (Catabolic)
- reactant is broken down into products
Exchange Reactions
- AB + C > AC + B (e.g. Zn + 2 HCl à H2 + ZnCl2 )
- Also called displacement reactions
- Involve both synthesis and decomposition
- Bonds are both made and broken
Rate
how quickly reactants are formed into products, regardless of the type of reaction.
The rate of chemical reactions are affected by:
- Temperature (increased temp, increased rate)
- Concentration of reactant (increase concentration, increased rate)
- Particle size (decreased particle size, increased rate.
- Catalysts increase Rate without being chemically changed or part of product
•Enzymes are biological catalysts
Chemical reactions are essential for all cells all the time!! Most do not occur naturally at a fast enough rate to provide products needed to stay alive. _____________ inside our cells are crucial for making the reactions occur fast enough to sustain life.
Enzymes
molecular weight
The sum of the atomic weights in a molecule is the molecular weight
One ________of a substance is its molecular weight in ___________.
- mole
- grams
- ex.
H2O
2H = 2 x 1 = 2 (2 hydrogen molecules times its molecular weight)
O = 16 (1 oxygen molecule’s molecular weight)
MW = 18 (moleclar weight of both)
1 mole weighs 18 g
cells contain about _______in the cytoplasm and are generally “bathed” in __________.Therefore all reactions are taking place in what we call an _______________ and for the most part all components of that reaction, including reactants, enzymes, and products, are _______ in water.
- 75% water
- watery fluid
- aqueous or watery enviornment
- dissolved
Solution
- Solvent (liquid) + solute(s) (dissolved particles), e.g. Kool Aid (water is solvent, Kool Aid powder and sugar are dissolved solutes)
- Solutions are often described in terms of their CONCENTRATION, or the amount of solute dissolved.
- In chemistry, this was sometimes referred to as molarity or molar concentration. The higher the molarity, the more solute per given volume of solvent
pH
is a measure of [hydrogen ion]
The pH scale ranges from _______.
0-14
a pH of 0-6.99 is _______.
acidic
a pH of 7.00 is ________.
neutral
a pH of 7.01-14.0 is _______.
basic
a pH scale is ___________. A pH 5 solution is ____times more acidic than a pH 6 solution and _______times more acidic than a pH 7 solution
- logarithmic
- 10
- 100
Another important aspect of the environment in which chemical reactions occur is the pH (“power of Hydrogen”). pH is important because it affects the ______at which chemical reactions occur, and must be _________ in order for the body to function properly.
- rate
- homeostatic
Acids are _______donors.
- proton
- Release H+ (a proton, or hydrogen ion) in solution
- HCl > H+ + Cl–
- HCl, HC2H3O2 (HAc), and H2CO3
Bases are proton ______.
- acceptors
- Take up H+
- Na+ + OH–
- OH– accepts an available proton (H+)
- OH– + H+ à H2O
- Bicarbonate ion from solution (HCO3–)
- NaOH and ammonia (NH3)
relative free [H+] of a solution is measured on the ___________.
- pH scale
As [OH-] decreases and [H+] increases…
- acidity increases
- pH lowers
As free [H+] decreases…..
- alkalinity increases
- [OH–] increases as [H+] decreases
- pH increases
Functional groups
Functional groups bond to carbon skeletons and are responsible for most of the chemical an physical properties of a particular organic compound
Name this group, why is it impotant biologically?
- Alcohol
- lipids and carbohydrates
Name this group, why is it important biologically?
- Aldehyde
- reduces sugars such as glucose; polysaccarides
- in and aldehyde molecule the carbon oxygen double covalent bond is on the end of the molecule.