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nature of chemistry 1 Flashcards

(45 cards)

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1
Q

Chemistry

A

study of matter, interactions involves experimenting in macroscopic world and theorizing about microscopic world

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2
Q

Empirical knowledge

A

comes from investigation and observation

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3
Q

Theoretical knowledge

A

Explains scientific observation: based on ideas created to explain

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4
Q

Theory

A

explanation /model based on observation reasoning experimentation
- why something happens
predicting

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5
Q

Law

A

explain observation either as statements or mathematical equation
-proven consistently

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6
Q

What did greek philophers discover?

A
  • matter can be subdivided into tiny particles calle atomos(cant be cut )
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7
Q

Democritus

A

atom exsistence
different sizes,constant motion

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8
Q

Aristole

A

matter is made up of earth, water ,fire, air

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9
Q

Dalton

A

Law of conservation of mass
- atoms are rearranged to form new substances but never created or destroyed

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10
Q

JJ thompson

A

-used a cathode ray tube to discover the existence of electrons
- electrons are small (-) particles(plum pudding model)

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11
Q

Rutherford

A

nuclear model
- aimed + alpha particles at gold foil and measured how many alpha particles deflected off the foil on a fluorescent screen
COnclusions:
most were absorbed by foil and only some were deflected
Nuclear model: atom contains small dense positive centre

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12
Q

Chadwick

A

Exsistnece of the neutron confirmed

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13
Q

Bohr

A

Electrons existed in energy levels
Planetary model: electrons orbit the nucleus in definite energy levels (shells) can jump and transfer.

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14
Q

Ground state

A

when electrons in an atom have the lowest amount of energy possible for the location that they are at in the element

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15
Q

Excited state

A

when energy is added in the form of heat or electricity to an atom
electrons absorb energy which allows them to jump to a higher energy level

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16
Q

Emission spectrum

A

pattern of electron movement= ands of certain wavelengths of coloured light
- used to identify unknown samples
purple= far electron jump
red= short electron jump

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17
Q

Isotope

A

atoms of the same element that have different # of neutrons but same p and e-

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18
Q

isotopic abundance

A

the % of a given isotope in a sample of an element

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19
Q

Radiation and radioisotopes

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A
  • some isotopes are stable while others break
  • difference in stability is due to the composition of the nucleus
  • large # of neutons destabilize the nucleus
20
Q

Alpha particles

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A

same structure as helium nucleus with a 2+ charge
- blocked by paper

21
Q

Beta particles

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A

-negatively charged e-
- blocked by aluminun

22
Q

gamma rays

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A

have no mass and travel at light speed blocked by lead

23
Q

trend

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A

predictable change in particular direction

24
Q

electron shielding

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A

inner electrons shield outer electrons from the full attractive force of the nucleus(protects valence shall from attraction

25
effective nuclear charge
charge felt by valence electrons after you have taken into account the # of shielding electrons
26
atomic radius
distance from center to outmost orbit
27
what happens to atomic radius as you move down the group ?
it increases as the electrons occupy consecutiveley higher energy levels farther from nucleus - ENC decreases due to increased shielding
28
what happens as you move across a period to radius?
atomic radius decreases - same number of orbits electrons are in same energy level -more nuclear charge (protons added moving left to right) - outermost electrons are pulled closer
29
what happens when you move down a group to ionization? what happens when you move across a period?
decreases due to increased electron shielding and decreased ENC - increases as you move across period, increas in ENC unchanged shielding
30
Electron affinity
the energy given off when an electron is added to atom to make an anion - high affinities form negative ions in IC - low affinities form positive ions in IC
31
EA trends
- decreases as you move down group due to increased electron shielding and decreased ENC - increases as you move across a period due to increasing nuclear charge unchanged shielding easy to gain e-
32
Electron negativity
measure of the ability of an atom in a compound to attract electrons in a bond - higher electronegativity means a stronger pull on e- - charges vary from 0-4
33
Radius of cations
-metals form cations - cations form by losing electrons - cations smaller then og atom as they lose an energy level - more e- lost = radius gets smaller - enc increases, shielding decreases.
34
radius of anions
-nonmetals form anions - anions form by gaining electrons - anions are bigger then og atom - have the same energy level and nuclear charge but more repulsion - radius get larger ENC decreases shielding unchanged repulsion increases
35
Ionic radius trends
-increases as you move down a group - decreased ENC as shielding is unchanged - decreases as you move across a period due to inccreasing nuclear charge - + ions left to right =higher ENC - - ions left to right ( less electrons are need to the right so e- and p count similar = less repulsion
36
ionization energy
energy required to remove an electron from an atom or ion - overcome attraction between e- and nucleus+
37
2nd ionization energy
the energy required to remove a second electron from a cation - needs more energy then 1st ionization as the nucleus became more + since first electron was lost
38
ionization energy group 1
group 1: easily loses its 1 valence e- - low first ionization energy - second ionization will be very high since the new valence is full
39
ionization group 2
- easily loses 2 valence e - - low first and second ionization energies - high third ionization energy since new shell is full
40
Electronegativity trends
- decreases as you move down a group due to decreases ENC and lots of shielding - increases as you move across a period increasing atomic #, increase in ENC and unchanged shielding metals have low electronegativity nonmetals have high electronegativity
41
dmitri medeleevs periodic law
when elements are arranged according to increasing atomic mass , periodic recurrence of properties occurs at regular intervlas
42
Alkali metals
- column 1, 1 valence e- - soft, silver, solids - reacts violently to make base
43
Alkaline earth metals
- column 2, 2 valence e- - solid - reacts with air to form oxide coatings - reacts with hydrogen to form hydrades
44
halogens
column 17 , 7 valence e- - solid, liquid, gas - dull and not a conductor - very reactive
45
noble gases
column 18 8 valence e- - gases - low melting and boiling point - inert (unreative)

Chemistry (2 decks)

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