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Chemistry > Unit 2 > Flashcards

Unit 2 Flashcards

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1
Q

Law of conservation of mass

A

mass is neither destroyed nor created during ordinary chemical reactions or physical changes

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2
Q

Dalton’s Atomic Theory

A
  1. all matter is composed of extremely small particles called atoms. (IMPORTANT)
  2. atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties.
  3. atoms cannot be subdivided, created, or destroyed. (false)
  4. atoms of different elements combine in simple whole-number ratios to form chemical compounds.
  5. in chemical reactions, atoms are combined, separated, or rearranged.

IMPORTANT: atoms of any one element differ in properties from atoms of another element remain unchanged + #1

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3
Q

Cathode Ray Tube

A
  • first discovery of a subatomic particle resulted from investigations into the relationship between electricity and matter
  • many experiments performed in which electric current passed through various gases at low pressures (gases at atmospheric pressures don’t conduct electricity well)
  • experiments carried out in cathode-ray tubes

-particles pass through tube from cathode, medal disk connected to negative terminal of voltage source, to anode, metal disk connected to the positive terminal

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4
Q

Rutherford’s Gold foil experiment

A
  • reasoned that the rebounded alpha particles must have experienced some powerful force within the atom and figured that the source of this force must occupy a very small amount of space
  • concluded that the force must have been caused by a very densely packed bundle of matter with a positive electric charge
  • rutherford called this positive bundle of matter the nucleus
  • he discovered the volume of nucleus was very small compared with the total volume of an atom
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5
Q

electromagnetic/electrostatic/coulombic force

A

unlike charges attract, like ones repel

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6
Q

nuclear force

A

the short-range proton-neutron, proton-proton, and neutron-neutron forces hold the nuclear particles together and are referred to as nuclear forces

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7
Q

radioactivity

A

-radioactivity refers to the particles which are emitted from nuclei as a result of nuclear instability.

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8
Q

chemical v nuclear reactions

A
  • nuclear reaction takes place in the atom’s nucleus, the electrons in the atom are responsible for Chemical reactions.
  • The chemical reactions involve the transfer, loss, gain and sharing of electrons and nothing takes place in the nucleus. Nuclear reactions involve the decomposition of the nucleus and have nothing to do with the electrons. When the nucleus decomposes, it may change to another atom because of the loss of neutrons or protons. In a nuclear reaction, the protons and neutrons react inside the nucleus and in chemical reactions the electrons react outside the nucleus.
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9
Q

protons, electrons, neturons

A
  • a proton has a positive charge equal in magnitude to the negative charge of an electron
  • atoms are electrically neutral bc they contain equal numbers of protons and electrons
  • a neutron is electrically neutral
  • number of protons in an atom’s nucleus determines that atom’s identity
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10
Q

atomic number and mass number

A
  • the atomic number of an element is the number of protons in the nucleus of each atom in that element
  • the mass number is the total number of protons and neutrons in the nucleus of an isotope
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11
Q

isotopes/nuclide

A
  • isotopes are atoms of the same element that have different masses
  • nuclide is a general term for any isotope of any element
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12
Q

nucleons

A

-a proton or neutron

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13
Q

atomic notation (nuclear symbol) and hyphen notation

A
  • hyphen notation: the mass number is written with a hyphen after the name of the element (hydrogen-3)
  • atomic notation shows the composition of a nucleus as the isotope’s nuclear symbol (uranium 235 - 235/92U)
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14
Q

atomic mass unit (amu/u)

A
  • one atomic mass unit, or 1 amu, is exactly 1/12 of the mass of a carbon-12 atom.
  • although isotopes have different masses, they do not differ significantly in their chemical behavior
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15
Q

average atomic mass

A

-the weighted average of the atomic masses of the naturally occurring isotopes of an element)

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16
Q

mole

A

a special unit used by chemists to express amounts of particles, such as atoms and molecules (bc in most experiments, atoms are much too small to be measured individually; chemists can analyze atoms quantitatively, however, by knowing fundamental properties of the atoms of each element. this information is used to count the number of atoms of an element in a sample with a known mass)
-amount of a substance that contains as many particles as there are atoms in exactly 12g of carbon-12

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17
Q

Avogadro’s number

A
  • the numbers of particles in exactly one mole of a pure substance
  • crucial in explaining the relationship between masses and numbers of atoms
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18
Q

molar mass

A

-the mass of one mole of a pure substance is called the molar mass of that substance (g/mol)

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19
Q

electromagnetic spectrum

A

-together, all the forms of electromagnetic radiation form the electromagnetic spectrum

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20
Q

electromagnetic radiation

A

-visible light is a kind of electromagnetic radiation, which is a form of energy that exhibits wavelike behavior as it travels through space

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21
Q

wavelength, frequency, speed of light, energy of photon (Planck’s constant)

A

-wavelength is the distance between corresponding points on adjacent waves
-frequency is defined as the number of waves passing through a given point in a specific time, usually one second
c = wavelength x frequency
E = hv

E= energy (Joules), h=Planck’s constant, v=frequency of radiation emitted

22
Q

photoelectric effect

A

-refers to the emission of electrons from a metal when light shines on the metal

23
Q

ground state v excited state (emit vs absorb energy)

A

ground state: the lowest energy state of an atom

excited state: a state in which an atom has a higher potential energy than it has in its ground state

24
Q

spectroscope

A

-instrument used to measure properties of light over a specific portion of the electromagnetic spectrum

25
Q

quantum mechanical model

A

-quantum mechanical model is based on quantum theory, which says matter also has properties associated with waves. According to the Heisenberg Uncertainty Principle, it’s impossible to know the exact position and momentum of an electron at the same time.
-uses complex shapes of orbitals/electron clouds, volumes of space in which there is likely to be an electron based on probability
-four numbers, quantum numbers, were introduced to describe the characteristics of electrons and their orbitals:
Principal quantum number: n
Angular momentum quantum number: l
Magnetic quantum number: m1
Spin quantum number: m5

26
Q

heisenberg uncertainty principle

A

-states that it is impossible to determine simultaneously both the position and velocity of an electron or any other particle

27
Q

principle quantum number (n)

A

-indicates the main energy level occupied by electron, symbolized by n

28
Q

angular momentum quantum number (l)

A

-indicates the shape of the orbital, symbolized by l

29
Q

magnetic quantum number (m)

A

-indicates the orientation of an orbital around the nucleus, symbolized by m

30
Q

spin quantum number

A

-has only two possible values (+1/2,-1/2) which indicate the two fundamental spin states of an electron in an orbital

31
Q

aufbau principle

A

-states that an electron occupies the lowest-energy orbital that can receive it

32
Q

pauli exclusion principle

A

-pauli exclusion principle states that no two electrons in the same atom can have the same set of four quantum numbers

33
Q

hund’s rule

A

-hund’s rule states that orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron, and all electrons in singly occupied orbitals must have the same spin

34
Q

electron configurations

A

three methods/notations:

  • orbital notation
  • electron-config notation
  • noble-gas notation
35
Q

s,p,d,f = location of blocks, max number of electrons, number of orbitals

A
  • based on the electron configurations of the elements, the periodic tables can be divided into four blocks, the s, p, d, and f blocks. the name of each block is determined by whether an s, p, d, or f sublevel is being filled in successive elements of that block.
  • s block: chemically reactive metals, contains a single s electron
  • d block: appears when n=3, consists of five orbitals with a maximum of two electrons each, or up to 10 electrons possible in each d sublevel
  • p block: the total number of electrons in highest occupied level is equal to group number minus 10
  • f block: wedged between Groups 3 and 4 in sixth and seventh periods, reflecting the fact that they involve the filling of the 4f sublevel
36
Q

orbital

A

-a three dimensional region around the nucleus that shows the region of probable electron locations

37
Q

mendeleev

A

-mendeleev created a table in which elements with similar properties were grouped together - a periodic table of the elements

38
Q

periodic law

A

-the physical and chemical properties of the elements are periodic functions of their atomic numbers

39
Q

alkali metals

A

-the elements of group 1 of the periodic table are known as the alkali metals

40
Q

alkaline earth metals

A
  • the elements of group two of the periodic table are known as the alkaline-earth metals
  • contain a pair of electrons in their outermost s level
41
Q

transition metals/elements

A

-the d-block elements are metals with typical metallic properties and are often referred to as transition elements

42
Q

halogens

A

-elements of group 17

43
Q

noble gases

A

-elements of group 18

44
Q

lanthanides and actinides

A
  • lanthanides are the 14 elements with atomic numbers from 58 (Ce) to 71 (Lu)
  • actinides are the 14 elements with atomic numbers from 90 (Th) to 103 (Lr)
45
Q

main group elements

A

-the p-block elements together with the s-block elements are called the main-group elements

46
Q

valence electrons

A

-an electron that is available to be lost, gained, or shared in the formation of chemical compounds

47
Q

lewis dot structures

A

-formula in which atomic symbols represent nuclei and inner-shell electrons, dot-pairs/dashes between two atomic symbols represent electron pairs in covalent bonds, and dots adjacent to only one atomic symbol represents unshared electrons

48
Q

ionization energy

A
  • ion: an atom or group of bonded atoms that has a positive or negative charge. any progress that results in the formation of an ion is referred to as ionization. the energy required to remove one electron from a neutral atom of an element is the ionization energy, IE.
  • ionization energies of the main-group elements increase across each period, caused by increasing nuclear charge.
  • ionization energies generally decrease down the groups among the main group elements bc of the electrons removed from atoms of each succeeding element in a group, causing them to be removed more easily.
49
Q

electronegativity

A
  • measure of the ability of an atom in a chemical compound to attract electrons.
  • tend to increase across each period
  • electronegativites tend to either decrease down a group or remain about the same
50
Q

atomic size (radii)

A
  • defined as 1/2 the distance between the nuclei of identical atoms that are bonded together
  • the trend to smaller atoms across a period is caused by the increasing positive charge of the nucleus
  • in general, the atomic radii of the main-group elements increase down a group bc of the successively higher main energy levels located farther from the nucleus
51
Q

quantum number

A

a number that specifices the properties of atomic orbitals and the properties of electrons in orbitals

Chemistry (8 decks)

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