general chemistry - unit 1

unit 1 slay ( •̀ᴗ•́ )و ̑̑

what constitutes as matter?

anything that occupies space and has mass

what are the three most common states of matter?

solid, liquid, gas

what is a pure substance?

substance with constant composition

what is an element?

something that cannot be broken down into simpler substances by chemical changes

is H₂ an element?

yes, because it only consists of one type of element (hydrogen)

what is a compound?

something that can be broken down into simpler substances

do compounds share the properties of the uncombined elements?

no, the properties are different from the uncombined elements

is C₆H₁₂O₆ a compound?

yes, because it consists of different types of elements (carbon, hydrogen, oxygen)

what are the different kinds of mixtures?

homogeneous and heterogeneous

which type of mixture is uniform throughout, and considered a solution?

homogeneous

which type of mixture is not uniform throughout, and can be a simple, suspension, or colloidal mixture?

heterogeneous

what is an atom?

smallest particle of an element, and shares the properties of that element

who first proposed the idea of a small particle that made up everything in the world (an atom)?

Leucippus and Democritus (5th century bce)

who later backed up the idea of the atom?

John Dalton (19th century)

what is a molecule?

two or more atoms connected by chemical bonds

what was the machine created \~50 years ago that allowed the atom to be seen for the first time?

scanning-tunneling microscope (STM)

who created the law of conservation of mass, the first atomic law?

Lavoisier

what is the law of conservation of mass?

matter can neither be created nor destroyed

who created the law of definite proportions, the second atomic law?

Joseph Proust (1797)

what is the law of definite proportions?

all samples of any given compound (regardless of source or preparation) share the same properties as their constituent element

who created the law of multiple proportions, the third atomic law?

John Dalton (1804)

what is the law of multiple proportions?

when two elements form two different compounds, the masses of element B that combine with 1g of element A can be expressed as a ratio of small whole numbers

what was John Dalton’s general statement about elements and atoms?

each element is composed of atoms

what are the qualities that are unique between atoms of different elements?

mass and other properties

what are the kind of ratios that atoms combine in to form compounds?

simple, whole-numbered

what was John Dalton’s assertion about “transformation” of atoms?

atoms of one element cannot change into atoms of another element

what is an electron?

negatively charged subatomic particle

what is the charge of a single electron?

1\.6e-19C (coulombs)

charge to mass ratio of an electron?

1\.759e11C/kg

who discovered the electron and proposed the plum pudding model of an atom, as well as determined the mass and charge to mass ratio of an electron?

J.J. Thompson

how did Thompson discover the electron?

cathode ray tube experiment

who also discovered the electron, and determined the charge of a single electron?

Robert A Millikan

how did Millikan discover the electron?

oil drop experiment

what is the approximate mass of a single electron?

9\.107e-31kg

what is the nucleus?

relatively heavy and dense, positively charged subatomic particle in the center of an atom

who discovered the nucleus?

Ernest Rutherford

what did Rutherford conclude about the atom through his experiments?

atoms are mostly empty space with a nucleus in the center

what is a neutron?

uncharged (neutral) subatomic particle with a mass approximately the same as a proton, found in the nucleus

who discovered the neutron?

Chadwick (1932)

what is a proton?

positively charged subatomic atomic particle, found in the nucleus

what are isotopes?

atoms of the same element that differ in mass

what differentiates isotopes other than mass (what causes the difference in mass)?

varied number of neutrons

who discovered isotopes?

Fredrick Soddy (\~1921)

which isotopes tend to be more radioactive?

heavier isotopes

what is an ion?

an atom which loses or gains an electron

what is a cation?

ion that loses an electron (becomes more positively charged)

what is an anion?

ion that gains an electron (becomes more negatively charged)

what does the periodic law describe?

properties of elements are periodic functions of their atomic numbers

who created the periodic table?

Mendeleev

what are the three classifications of elements?

metal, nonmetal, metalloid

what is a metal?

shiny, malleable, good conductor of heat and electricity

what is a nonmetal?

appear dull, poor conductors of heat and electricity

what is a metalloid?

conduct heat and electricity moderately, possess some properties of metals and some of nonmetals

why is hydrogen used as the standard element or atom for experimentation?

because it only has one electron, it is simpler to obverse

what did Thomas Young demonstrate with the double slit experiement?

electrons behave both as particles and as waves

what are the valence electrons of any given element involved in?

bonding and reacting

who were the key people in the development of the quantum theory?

Planck, Einstein, de Broglie, Schrödinger, Heisenberg

why can’t electrons be observed?

observing them changes their behaviour

what is electromagnetic radiation?

the wave property of light

what did Isaac Newton discover related to the nature of light?

* white light consists of the individual colours of the rainbow combined
* light is composed of streams of small particles moving at high speeds

what did Thomas Young discover related to the nature of light?

* light passing through narrow slits produced interference patterns (double slit experiment)
* could only be explained in terms of waves

what did James Clark Maxwell discover related to the nature of light?

* discredit the particle view
* light is the visible portion of a spectrum of electromagnetic waves

what is the fundamental level on which particles and waves are connected?

wave-particle duality

what is the relationship between wavelength, frequency, and the speed of light

c=λv

what is the electromagnetic spectrum?

range of all types of electromagnetic radiation

what is constructive interference?

brightest regions of interference patterns, where both peaks or both troughs happen to coincide

what is destructive interference?

dark regions of interference patterns, where the peaks from one slit happen to coincide with the troughs from the other slit

what is a node?

point between the two end points of a wave that are not in motion, where the probability of finding electron is \~0%

who derived an expression for blackbody radiation to solve the ultraviolet catastrophe?

Max Planck

who used Planck’s quantization findings to resolve the photoelectric effect paradox?

Einstein

what is the relationship between the energy of a photon, Planck’s constant, and frequency?

E=hv

what is Planck’s formula?

E=hc/λ

how does the photoelectric effect show light to behave?

as particles

what equation did Johann Balmer use to explain the discrete lines?

1/λ=k(1/4-1/n^2)

how did Johannes Rydberg generalize Balmer’s work?

1/λ=k(1/n1^2-1/n2^2)

what did Rydberg’s generalization of the Balmer equation do?

predict all discrete lines for hydrogen (including ir and uv)

what explains line spectra of elements becoming more complicated (more lines) as the atomic number increases (generally)

more electrons ∴ more lines

what energy level does an electron have to relax to in order to give off discrete lines in the ir region?

→ n=3

what energy level does an electron have to relax to in order to give off discrete lines in the uv region?

→ n=1

what energy level does an electron have to relax to in order to give off visible light?

→ n=2

what is Bohr’s equation to calculate the energy level of an electron?

E=-2.18e-18J(Z^2/n^2), where Z = nuclear charge

when do electrons emit energy?

only when they go down in energy level

what equation is used to calculate the orbital energies of an electron?

|∆E|=|Ef-Ei|=hv=hc/λ

what does the Bohr model not account for?

electron-electron interactions

what is the de Broglie wavelength?

* characteristic of particles
* wavelength is inversely proportional to momentum (mv)
* λ=h/mv

true or false: the wave characteristics of an electron is irrelevant because it is so small

false, the wave character of electrons is significant __because__ they’re so small (small mass = large wave, large mass = small wave)

which two people demonstrated experimentally that electrons can exhibit wavelike behaviour?

C. J. Davisson and L. H. Germer

how did Davisson and Germer demonstrate that electrons can exhibit wavelike behaviour?

“shooting'“ electrons through a regular atomic pattern in a crystal

what did Heisenberg’s uncertainty principle show?

since position and velocity of a particle are complementary properties, the more you know about one, the less you know about the other, making it impossible to know both exactly how fast a particle is moving and its exact location at any given moment

what makes velocity and position complementary properties? (complementary principles)

velocity is related to an electron’s wave nature, position is related to an electron’s particle nature

what is the difference between determinacy and indeterminacy?

determinacy: definite, predictable

indeterminacy: indefinite, can only predict

what is a probability map?

representation of regions where an electron is *likely* to be found (not definite, predicted)

what did Schrodinger do?

generalized de Broglie’s work by incorporating the de Broglie relation into a wave equation

what does the principal quantum number, n, represent?

energy level of an electron

true or false: the larger the value of n, the larger the orbital

true

true or false: as n gets larger, the amount of energy between orbitals gets larger?

false, it gets smaller

what does the angular momentum quantum number, l, represent?

shape of the orbital

what is the block that consists of l=0 called?

s block

what is the block that consists of l=1 called?

p block

what is the block that consists of l=2 called?

d block