Chapter 2 - Chemical Foundation of Life Flashcards
What is matter?
any substance that occupies space and has mass
What is an element?
matter that is broken down until it cannot be broken anymore or transformed chemically into another substance
How many elements are there and how many occur naturally?
118 elements
98 occur naturally, rest unstable and need to be synthesized in laboratory
What are the 4 elements common in all living organisms?
Oxygen, Hydrogen, Carbon, Nitrogen
What is C?
Carbon
Atomic mass of 6
What is H?
Hydrogen
Atomic mass of 1
What is O?
Oxygen
Atomic mass of 8
What is N?
Nitrogen
Atomic mass of 7
What is Na
Sodium
Atomic mass of 11
What is P?
Phosphorous
Atomic mass of 15
What is Cl?
Chlorine
Atomic mass of 17
What is a cm = to?
10 ^-2 m
What is a mm = to?
10 ^-3 m
What is a micrometer = to?
10 ^-6 m
What is a nanometer = to?
10 ^-9 m
What is a picometer = to?
10 ^-12 m
What is a fentometer = to?
10 ^-15 m
Which is bigger : molecules or compounds?
Molecules are bigger; a compound is a type of molecule, so all compounds are molecules, but not all molecules are compounds
What is an atom comprised of?
2 regions:
nucleus - atom’s center, contains proteins and neutrons
outer region - holds electrons in orbit around nucleus
- contains protons, neutrons, electrons
Protons vs Neutrons
Approx the same mass - 1.67 x 10 ^-24, defined as one atomic mass unit (amu) or Dalton
-Protons positive charge
-Neutrons uncharged
Atomic Number is determined by…
number of protons
-used to distinguish one element from another
Background on Electron
much smaller in mass than protons
-9.11 x 10 ^-28 grams
-1//1800 of an atomic mass unit
-don’t contribute as much to elements’ overall atomic mass
-typically ignore the mass of any electrons and calculate atomic mass based on protons and neutrons alone
Charges of Electrons and Protons and Neutrons
Protons - positive
Electrons - Negative
Neutron - Uncharged
In uncharged, neutral atoms the number of electrons…
equal the number of protons, charges cancel out
What are Isotopes?
different forms of the same atom that vary only in the number of neutrons they possess
What is the mass number?
the number of protons and neutrons in an element, bottom number of periodic table
What is the Periodic Table?
organizes and displays different elements
-created by Dmitri Mendeleev in 1869
-groups elements that share certain chemical properties
-properties are responsible for physical state at room temp (gas, liquid, solid)
What is Chemical Reactivity?
ability to combine and chemically bond with each other
-differences based on the number and spatial distribution of an atom’s electrons
When two atoms bond, what comes together first?
the electrons (outermost region)
What is the Bohr Model?
-orbitals specific distance from the nucleus; electrons fill orbitals closest to nucleus first and then orbitals of increasing energy further from the nucleus; if multiple orbitals with = energy, they fill one electron in each energy level before adding a second electron
-orbits form electron shells or energy level
Electrons at the highest level are called…
valence electrons
Electrons of outermost energy level determine…
an atom’s energetic stability and tendency to form chemical bonds with other atoms
What is the octet rule?
innermost shell has max 2 electrons but the next two electron shells can have max 8 electrons
-atoms more stable energetically with 8 electrons in a valence shell (outermost electron shell)
Atoms want to get full valence shell to be more stable, so what can they do…
give, take, share electrons with each other
What are inert gases?
AKA Noble Gases
non-reactive
Electron Orbitals
-relatively complex shapes
-results from the fact that electrons behave not just like particles, but also like waves
-not like Bohr Model, not like Earth & Sun
-SPDF –> designate subshells
-S : spherical, one orbital
-P : 3 dumbbell shaped orbitals
-D,F : more complex shapes, contain 5 + 7 orbitals (respectively)
What are salts?
Compounds that dissolve in water and produce cations other than H+ and anions other than OH -
What is intermolecular attraction?
neighboring molecules also attracted to one another
Chemical Reactions
-occur when 2+ atoms bond to form molecules or when bonded atoms break apart
What are reactants?
substances used in beginning, usually left side of equation
What are products?
substances at end of reaction, usually right side of equation
Balanced Chemical Equation
each element’s number of atoms is the same on each side of the equation
Law on Conservation of Matter
number of atoms before and after a chemical reaction should be equal, such that no 2 atoms are (under normal circumstances) created/destroyed
What is a Homonuclear Molecule?
double bond of same element
Irreversible Reactions
can proceed in 1 direction until they expend all reactants
-unidirectional arrow
Reversible Reactions
can go either direction
-reactants turn into produces until a certain threshold and some of these products convert back into reactants
-back and forth until equilibrium = balance b/w reactants and products occur double headed arrow
Reversible Reactions
can go either direction
-reactants turn into produces until a certain threshold and some of these products convert back into reactants
-back and forth until equilibrium = balance b/w reactants and products occur double headed arrow
What are cations?
+ ions that form by losing electrons
What are anions?
- ions that form by gaining electrons
elemental name : change ending to “ide”
Electron Transfer
movement of electrons from one element to another
Ionic Bonds
form b/w ions with opposite charges, transfer of electrons
Electrolytes
ions necessary for nerve impulse conduction, muscle contractions, water balance (sodium, potassium, calcium)
Covalent Bonds
sharing of electrons
-stronger, more common than ionic in molecules of living organisms
-single, double, triple bonds (strongest)
-more covalent bonds b/w 2 atoms, stronger the connection
Hydrogen Bonds
electrostatic attraction b/w positively charged hydrogen atoms of 1 water molecule and negatively charged oxygen atoms of another
-weaker, common, provide many critical life-sustaining properties of water and stabilize structures of proteins and DNA
Strength of Chemical Bonds
covalent - ionic - hydrogen - vanderwaals
weak bonds are used to : reinforce shapes of large molecules, help molecules adhere to each other
Polar Covalent Bond
atoms unequally share the electrons and are attracted more to one nucleus than the other
-slightly + or - charge
Electronegativity - more attractive
Nonpolar Covalent Bonds
form b/w 2 atoms of the same element or b/w different elements that share electrons equally
Nonpolar Covalent Bonds
form b/w 2 atoms of the same element or b/w different elements that share electrons equally
How much of the human body is water?
60-70%
What kind of bond makes water?
-Polar Covalent Bond
-slightly + charge on H and slightly - on O
-O is more electronegative than H which generates partial - charge near O
-water molecule attracts other water molecules and other polar molecules/ions
What does Hydrophilic mean?
polar substance that interacts readily with or dissolves in water
What does Hydrophobic mean?
nonpolar compounds/molecules that don’t interact well with water
-oils, fats, vinegar
What is Specific Heat?
amount of heat one gram of a substance must absorb or lose to change its temp by one degree Celsius
-water has the highest specific heat capacity of any liquids, one calorie
What is Heat of Vaporization
amount of energy required to change one gram of a liquid substance to a gas
-high for water, 586 calories b/c H bonding makes it more difficult to separate liquid H2O molecules
What is an Acid?
any ionic compound that releases hydrogen (H+) in a solution, concentration of hydrogen ions
What is a Base?
any ionic compound that releases hydorxide (OH-) in a solution, raises pH
Redox Reaction
chemical reactions in which electrons are gained, lost, or shared in chemical reaction
Oxidation
the loss of electrons (oxidized compound)
Reduction
the gain of electrons (reduced compound)
Solvent
substance capable of dissolving other polar molecules and ionic compounds
Sphere of Hydration
AKA Hydrogen Shell, charges of molecules form hydrogen bonds with water, surrounding the particle with H2O molecule
-keeps particles separated or dispersed in water
Dissociation
occurs when atoms or groups of atoms break off from molecules and form ions, when ionic compounds to water and the individual ions react with water molecules’ polar regions and their ionic bonds are disrupted
Cohesion
water molecules are attracted to each other (b/c H bonding), keeping molecules together at liquid-gas interface
-allows for surface tension
Surface Tension
the capacity of a substance to withstand rupturing when placed under tension or stress (floating needle on top of the glass of water)
Adhesion
the attraction between water molecules and other molecules
-stronger than cohesion
-capillary action (like plants’ roots or water striders)
pH?
Concentration of hydrogen ions
-tested using litmus paper
Mole
way to express the amount of a substance
-1 mole = 6.023 x 10^23 particles of substance (Avogadro’s #/constant)
If you increase the # of Hydrogen ions, the pH ___?
decreases
If you decrease the # of Hydrogen ions, the pH ___?
increases
pH scale
inverse logarithm, ranges from 0 - 14
less than 7 = acidic
greater than 7 = basic
7 = neutral
Buffers
readily absorb excess H+ or OH-
-keeps body’s pH carefully maintained in a narrow range for survival (antacids -> combat excess stomach acid)
Organic Compound
any carbon-containing liquid/solid/gas
-macromolecules are subsets, like proteins, RNA/DNA, carbs, lipids
-fundamental component for those macromolecules = carbon
-covalent
-less energy required
-low boiling/melting point
-complex structure
Inorganic Compound
compounds that are not organic, generally not made of carbon, generally small molecules, usually consist of atoms joined by ionic bonds
-electrolytes (acids, bases, salts)
-ionic
-high boiling/melting point, soluble in polar solvents, simple structure
-more energy required
Organic Compound Examples
sugar, lipid, DNA, Ribose, Ethanol, Methane
Inorganic Compound Examples
salt, CaCl2, Carbon Dioxide (CO2, ionic bond), Silver, Diamond
