Chem test 3 - Light and Electrons

electromagnetic radiation speed

3.00 x 10^8 m/s - it all moves at the same speed

frequency

the number of complete wavelengths that pass a point in a given time

The energy of visible light

low energy - high energy
red - violet

The Photoelectric Effect

The emission of electrons from a material when high frequencies of light (orange-violet) shine on the surface of the material

dual nature of matter

matter can have properties of both a particle and a wave
- light can act + others
- the more massive the object, the smaller its wavelength

wave nature of electrons

- Tiny, fast-moving particles also behave as waves (this explains electron energy levels) proved by interference pattern vs two lines

Bohr Energies model

- each level of energy gets closer to the one before it
- there are an infinite number of levels but they eventually get so close its hard to tell them apart

energy absorption

if an electron that's not charged gets struck by a photon with the right energy it jumps to a higher, possible state, and then falls releasing a photon with energy equivalent to the jump/fall made

energy emission

after an atom is excited it returns down to its ground state, it emits a photon of energy in the form of electromagnetic radiation (light) that correlates with the size of energy/jump ex: big jump+energy = high energy radiation like UV

the smaller the energy...

the higher/longer the wavelength

light emission spectrum (bohr)

pattern of lines formed - each spectral line corresponds to a different electron transition from a higher to lower energy state - different atoms give certain colors based on electrons orbits - different charges gives different locations of electron orbits

limitations of planetary model

electrons don't orbit like planets, they have regions in which they are likely to exist

Orbitals/region of probability

regions around the nucleus in which given electron or electron pair is 90% likely to be found - but can be anywhere/is everywhere

Superposition

electrons are mathematically everywhere until you search for it and its in one place (sports game has all possible outcomes until you watch the game play out)

valance electrons

the number of electrons in the outermost shell

the # of orbitals is _____ and # of electrons are

the rings/orbitals squared and the orbitals^2 x 2

exceptions to electron configuration

Cr
expected: [Ar] 4s^2 3d^4 actual: [Ar] 4s^1 3d^5
Cu
expected: [Ar] 4s^2 3d^9 actual: [Ar] 4s^1 3d^10

periods on periodic table

horizontal rows

families or groups on the periodic table

vertical columns (skipping d block)

The Octet Rule

Atoms gain or lose electrons to obtain 8/full outer shell/a charge of 0 + metals loose electrons & gasses gain electrons

alkali metals

- group 1 of the periodic table
- extremely reactive
- very soft
- reacts strongly with water
- have one valence electron (will often lose to form +1 ions)

alkaline earth metals

- group 2 on the periodic table
- very reactive but less then alkali metals (cannot be found in nature)
- soft, but less then alkali
- have two valence electrons (will often lose +2 ions)

transition metals

- groups 3-12 (d block) on periodic table
- less reactive then 1-2
- stronger, harder, high melting points than groups 1-2; what u think of metals
- most have 1-2 valence electrons (variety of charges +1-+3 bc d block)

Lanthanides and Actinides

- groups (f block)
- inner transitional metals
- lanthanides are reactive, silvery metals (row4)
- actinides are all radioactive (row5)

Halogens

- Group 17 of the periodic table
- very reactive non metals
- mostly found diatomic (together) in nature (F2)
- Have 7 valence electrons (will often gain 1 to form -1 ions)

noble gases

- Group 18 of the periodic table
- mostly unreactive
- full valence shells (do not form ions)
- all are gasses (unless veryyyyyy cold)

Properties of metals

- Malleable (can be bent and molded)
-Ductile (can be drawn into wires)
-Have luster (shiny)
-High melting points (mostly solids at room temperature, except mercury)
-Good at conducting heat and electricity
-High density
-Often react with acids
-Typically lose electrons to form positive ions

The metals in the periodic table are _______

left of staircase (not touching)

properties of nonmetals

-Brittle (shatter, rather than bend)
-Dull
-Low melting points (mostly gases at room temperature, though not all)
-Poor conductors of heat and electricity
-Low density
-Usually less reactive with acids
-Typically gain electrons to form negative ions

the nonmetals on the periodic table are ____

right + up of staircase (not touching)

the semimetals/metalloid on the periodic table are _____

directly to the right of staircase

s orbital

- sphere shape
- group s
- holds 2 electrons

p orbital

- dumbbell shape
- group p
- holds 6 electrons

d orbital

- flower (dumbell + donut) shape
- group d
- holds 10 electrons
(its the center image in example photo)

f orbital

- very complex shape
- group f
- holds 14 electrons

atomic radius

size of an atom/ its radius:
- one-half the distance between the nuclei of identical atoms that are bonded together
Trend:
- as u go down table, atoms get bigger
- as u go right the table, atoms get smaller (bc protons pull orbital in)
- more electrons = bigger atom bc more repulsion in cloud/between orbitals

ionization energy

how much energy it takes to remove an electron from an atom
- ionize - turn an atom into ion
Trend:
- as u go down table/atoms get more shells its easier to remove electrons
- as u move right table/atoms get more protons/ its harder to remove bc higher IE

IE in metals and nonmetals

- metals don't want e = lower IE
- nonmetals want e = higher IE

Successive Ionization Energies

energies required to remove electrons beyond the first electron
- each successive electron is harder to pull of because there is more positive energy
- energy jumps occur when trying to pull off non-valence electron (off inner shell)

Electronegativity

how well an atom can attract an electron
Trend:
- as u go up/get less shells = higher electronegativity
- as u go right of table/get more protons = higher electronegativity

Reactivity

how easily an element will combine or start a chemical reaction with other substances
- metals usually react by losing electrons
trend: down to left/more shells, less p = more reactive
- nonmetals usually react by gaining electrons
trend: up to right/less shells, more p = more reactive
- generally you don't compare reactivity of metal to nonmetal

Zeff

effective nuclear charge= amount of pull felt by the outer electrons by the nucleus

Zeff explains...

atomic trends: as you move down a column atoms get larger despite the fact that doing so add protons (which usually makes atoms smaller) because Zeff spreads pull to all electrons
- atoms in first column have same Zeff, 1

Z represents

the variable z represents the atomic number of an atom/ its nuclear charge/ # of protons

Zeff on valence electrons

Zeff = (# of protons)-(#of core elctrons)
electrons dont feel full power of nuclear charge
- the charge is lessened by electrons in inner shells

Zeff shortcut

for NEUTRAL atoms:
Zeff=valence electrons bc
protons=electrons
electrons=core e+valence e

Zeff for ions

- find w/ electron configuration
- find amount of valence electrons
- ex: zeff for NA+ = 8 bc 1s^2, 2s^2, 2p^6

Dimitri Mendeleev

created the 1st periodic table according to atomic mass
- there were some gaps and predicated there were elements we didnt know (questioned spot of I)
- in order for As to be next to P (the more similar atom) there had to be two elements between Zn and As
- Te and I should be swapped based on atomic mass but dimitri left them based on the elements they were most similar to in terms of properties, and questioned Te mass (which was right in end)

Henry Moseley

Arranged the periodic table by atomic number instead of mass number bc he discovered way to find the charge of atoms nucelus (atomic #)
- solved issue of atomic mass order with Te and I
- know where the gaps go bc whole number of atomic mass

Metals can be...

pure or as compounds often in solutions

when do metals/nonmetals react to each other

- a lone element attempts to replace another element in a compound (will replace if its more reactive)
- A+BC --> AB + C

electromagentic spectrum

all the forms of electromagnetic radiation - and are energy that can w/o a medium

Isoelectronic

Having the same electronic configuration, although consisting of different elements