Chemistry

Mendel used garden peas to study heredity in an 8 year experiment, and discovered 7 different characteristics of pea plants, that he could study in an either-or form
He looked for patterns of inheritance throughout his many experiments
Mendel demonstrated with pea plants that both parents pass on to their offspring genetic factors that remain separate generation after generation
A gene is now defined as a segment of DNA whose sequence of nucleotides codes for a specific functional product; these products include ribosomal and transfer RNA and proteins
Most genes exist in more than one form, or allele; each allele of a particular gene has a different base sequence
The color variations observed by Mendel in his experimentation were probably due to differences between alleles of genes that encode enzymes involved in pigment synthesis

Chemistry

Eukaryotic chromosomes are long molecules of DNA wrapped around proteins; only part of this DNA codes for proteins; noncoding DNA is not translated
About 1% of eukaryotic DNA is expressed as protein
Prokaryotes, including bacteria, have a single circular chromosome with little associated protein, they don’t have introns, and an estimated 90% of their DNA is translated; many bacteria also have plasmids ; which are small circles of DNA that contain additional genes
Genetic engineers use plasmids to introduce modified genetic material into bacterial cells; plasmids also can carry genes that provide resistance to antibiotics
Chromosomes are easiest to study in the condensed form they have during cell division
Chemicals are added to cultured white blood cells, in order to make them stop in metaphase
Individual chromosomes can be cut out of an enlarged photograph and arranged by size and shape to form a display called a karyotype

Chemistry

The environment has a strong impact on gene expression
Fraternal twins are no more genetically similar than other siblings
Both genes and environment are important
According to the theory of blending inheritance, an individual’s genetic makeup was formed when the parents’ genes mixed at fertilization
Blending inheritance was a logical explanation for many visible differences, but is no longer included in genetic inheritance theories

Chemistry: Thomson's Plum Pudding Model

Thomson’s plum pudding model consisted of a large, positively charged atom in which electrons were present.

Rutherford recognized a fault in Thomson’s plum pudding, claiming that electrons revolved around what he called the “nucleus”, which was a small core at the center of the atom containing all of that atom’s positive charge.

Chemistry Notes

Chemistry is the study of all substances and the changes that they can undergo
Chemistry is called the central science b/c it overlaps so many sciences
The scientific method is a way of answering questions about the world we live in
Steps of the method: observation => question => hypothesis => experiment => conclusion
The variable is the factor being tested

An experimental control responds in a predictable way to the experiment
Mass (kg), length (m), time (s), quantity (mole), temp. (K), electric current (ampere), luminous intensity
(candela), area (m2), volume (m3), force (Newton), pressure (pascal), energy (joule), power (watt),
voltage (volt), frequency (hertz, Hz), electric charge (coulomb, C), NON-SI: volume (liter), pressure
(atm, measured in mm Hg), temp. (Celsius), energy (calorie, cal)

Measurements are uncertain for two reasons: measuring instruments aren’t flawless and measuring always
involves some estimation
A correct answer is an accepted value for a measurement
The certain digits and estimated digit or a measurement are together called the significant digits
A measurement can be compared with its accepted value by calc. its percent error: (measured value –
accepted value) / accepted value

Density is calc. by dividing mass by volume
Speed = distance / time, pop. Density = pop. / area
Converting between units is called dimensional analysisFour step problem solving strategy: analyze, plan, solve, evaluate
Energy is the capacity to do work or produce heat
Potential, kinetic, and radiant energy
0 K and -273 C is absolute zero
Physical changes don’t alter the identity of the substance, while chemical changes do
Law of conservation of matter/energy

An element is a substance that cannot be separated into simpler substances by a chemical change,
a pure substance
Two or more elements combine to form a compound
A mixture is a blend of two or more pure substancesHeterogeneous mixture has visibly different parts, while a homogeneous mixture doesn’t
Ionic bond: pos. charged ion attracted to a neg. charged ion
Ionic compound composed entirely of ions
Pos. charged ions called cations, neg. charged called anions
Octet rule- atoms tend to gain, lose, or share electrons in order to
acquire a full set of valence electrons
(Gilbert) Lewis Dot Diagrams are an easy way to represent valence
electrons making them popular

To name a monatomic anion, replace the suffix with –ide
All ionic compounds are electrically neutral
Monatomic/polyatomic ions- only one atom/more than one atom
Binary ionic compounds contain ions of only two elementsEmpirical formula is same as chemical formula

A covalent bond is formed by a shared pair of electrons between two atoms
A substance of molecules is a molecular substance
A molecular formula tells how many atoms are in a single molecule of a
compound
A structural formula specifies which atoms are bonded to each other in a
molecule

When one atom is significantly more electronegative than another, a covalent
bond
between them is said to be polar- the atom with greater electronegativity gains
a slight negative charge because it has a slight excess of electron density
When in a bond, when both atoms exert an equal pull on the electrons in the
bond, the bond is noonpolar
Chemists name a compound according to the atoms and bonds that compose it
Ionic compounds that absorb water into their solid structures form hydrates
Anhydrous substances are water-free

Electronegativity difference: <0.4>0.5, < 1.9 is polar covalent, and >2.0 is ionic
1+: hydrogen, sodium, potassium, ammonium (NH4+), lithium, silver, copper
2+: magnesium, iron, cobalt, nickel, calcium, zinc, copper
3+: aluminum, iron, cobalt, nickel
1-: fluoride, chloride, bromide, iodide, hydroxide (OH-), hypochlorite (ClO-),
nitrate (NO3-), bicarbonate (HCO3-), acetate (C2H3O2-)
2-: oxide, sulfide, sulfate (SO4 2-), carbonate (CO3 2-),
3-: nitride, phosphide, phosphate (PO4 3-)
To make an acid, take the base element, find cation/anion number, put that
on the end of an H, and at the (H + number) to the front of the compound
in question to make the acid
Mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca
OH- (hydroxide), NO3 – (nitrate), CO3 -2 (carbonate), SO4 -2 (sulfate),
PO4 -3 (phosphate) Two elements- ide ending
Whenever there’s 1 less oxygen than expected, change suffix (-ate -> ite)Transition metals need roman numerals, nonmetals need prefixes

A line spectrum contains only certain colors or wavelengths
The number of protons in an atom is its atomic number
When an atom loses or gains one or more electrons, it acquires a net electrical charge and is
called an ion
Atoms with the same number of protons but different numbers of neutrons are called isotopes
The strong nuclear force holds together the contents of the nucleusNuclear reactions change the composition of an atom’s nucleus