#1 Chem Quiz

blackbody

perfect black obj that does not refect any light but emits light if you increase the temperature

frequency (f)

the number of cycles per time, units s^-1 , Hz

wavelength (λ)

the length of a wave, units m

wave equation

(f)(λ) = c

speed of light constant ( c )

3.00 × 10⁸

quantum

specific landa

what are the 3 types of atomic spectrums?

1. visible spectrum

2. emission spectrum/bright line spectra

3. Absorption spectra/darkline spectra

what is a continous spectrum/visible spectrum?

spectrum where a prisim can be used to split up white light into all of its colours

how is a continous spectrum/visible spectrum produced?

white light → prisim/spectrophotometer → spectrum

what is a bright line/emission spectrum?

spectrum where each element emits a certain wavelength of light when heated

how is a bright line/emission spectrum produced?

heated up element → spectrophotometer → line spectrum

what is a absoprtion spectra/darkline spectra?

spectrum where a cold element gas absorbs a certain wavelength of light, done when placed in front of white light

how is a absorption spectra/darkline spectra produced?

white light → cold element → spectrophotometer → absorption spectrum

photoelectric effect

light energy (EM) can give electrons enough energy to leave a substance

Classic theory

• as light gets brighter (more energy waves), electrons absorb more energy and are more likely to be emitted from the substance

• classic theory was wrong

• more intense light did not change the amount of energy liberated

what did max plank propose?

• Max Plank proposed that light travels as a quantum of energy waves

• minimum amount of energy needed/certain wavelength to give enoguh electrons to leave a substance

what is the visible light spectrum range?

700nm - 400nm

what is the visible light spectrum colours?

ROYGBV

list the waves from longest wavelength to shortest wavelength.

1. radiowaves

2. microwaves

3. infared

4. visible

5. UV

6. x-rays

7. gamma rays

what is the menomic to memorize the electromagnetic spectrum from longest wavelength to shortest wavelength (lowest energy & frequency, to highest energy and frequency)?

Raging martians invaded venus using x-ray guns

what is plank equation? (energy of photon)

E = hf

what is the h constant?

6.63 × 10^-34

using the absorption spectra and emission spectra for the same element, what did bohr conclude?

an atom of an element can only absorb and emit certain wavelengths of energy

stationary state

electrons do not emit energy but they constantly orbit the nucleus

excited state

the farther away the orbit, the higher the energy level. electrons can absorb energy waves to jump to higher energy orbitals

what did balmer do?

he calculated the amount of photon energy released when electrons jumped back to a certain ground state for hydrogen

What is the balmer series?

• 6th, 5th, 4th, 3rd to 2nd shell

• 400-700 nm

• visible spectrum

What is the lynmann series?

• 6th, 5th, 4th, 3rd, 2nd, to 1st shell

• UV light

Paschen series

• 6th, 5th, 4th to 3rd shell

• Infared light

Energy of an electron in a shell formula

E=\frac{-2.18x10^{-18}}{n^2}

Energy released

E=E_{h}-E_{l}

• h = higher shell

• l = lower shell

What are quantum numbers?

advances in the quantum mechanical model was made to explain new observations of atomic spectra

principal quantum number (n)

• n represents the energy level of a orbital

• EX n=1 → 1st shell

• n² = # of orientations

• 2n² = # of electrons in that shell

secondary quantum number (ℓ) & scientist

• ℓ represents the type of subshell orbital

• Sommerfeld noticed that if you looked closer at a bright line spectra some lines were actually made up of 2 or more lines packed together

ℓ = 0

s orbital

ℓ = 1

p orbital

ℓ = 2

d orbital

ℓ = 3

f orbital

magnetic quantum number (m_ℓ) & scientist

• m_{\ell} represents the # of different orientations of each subshell

• Zeeman noticed that when a strong magnetic field was put near an element its bright line spectrum lines split

• proposed that each type of subshell orbital had different orientations in space

how do you calculate m_ℓ ?

-ℓ to +ℓ (possible values)

magnetic spin (m_s)

• m_s represents the electron spin in each orbital

• 2 electron per orbital

• one electron spins clockwise, other spins counter-clockwise

what does m_s = +1/2 mean?

unpaired electron

what does m_s = -1/2 mean?

paired electron

Louis de Broglie

• theorized that electrons do not move in circular orbits but in a wave

what does the formula \lambda=\frac{h}{mv} tell you?

wavelength of electron depends on mass and velocity

Werner Heisenberg

• came up with the Heisenberg uncertainty principle

• impossible to know the exact position and speed of a electron at the same time

• probability of location of a electron is 90-95% accuracy

Schrodinger

• invented wave equations (quantum mechanics) to determine the electron probability density (orbitals)

What did the bohr and quantum mechanical model have in common?

• protons and neutrons in the nucleus

quantum mechanical model

• translational movement around the nucleus in an energy level in a space called an orbital

• different shapes of orbitals

• 2 energy levels

s orbital

• 1 orientation

• 2 electrons max

p orbital

• 3 orientations

• 6 electrons max

d orbital

• 5 orientations

• 10 electrons max

f orbital

• 7 orientations

• 14 electrons max

Aufbau principle

electrons must fill orbitals in order of lowest to highest energy

Pauli exclusion principle

max of 2 electrons per orbital

Hunds rule

orbitals must be half filled first in an energy level before paring up

What is the exeption when an electron will jump?

jump from an s to a d orbital so it is half filled or fullly filled, only applies to d⁴ and d⁹

Strength of ferromagnetisim

strongly magnetic

Strength of paramagnetism

weakly magnetic

which is found in nature, ferro or para?

ferro

give 3 examples of ferromagnetic metals that are found naturally?

iron, cobalt, nickel

Why are ferromagnetic metals stronger?

lots of atoms work together — their tiny magnetic fields all line up in the same direction, creating strong regions called magnetic domains.

why are paramagnetic metals weaker?

• each atom with unpaired electrons makes a tiny magnetic field, but they don’t all line up together, so the effect stays weak

• unpaired electrons spin and partially align with the external magnetic field

Persistence for ferromagnetisim

Magnetism can remain even after the external magnetic field is removed

Persistence for paramagnetisim

Magnetism disappears when the external magnetic field is removed

Dalton

• each atom of the same element are exactly the same

• atoms are the smallest unit of matter and are indivsible

Law of Definite Proportions/Constant composition

elements of a specific compound have constant portions by mass

Law of multiple proportions

transition metals that are mutlivalent (multiple charges) can form different compounds

Law of conservation of mass

the total mass of reactants has to equal the total mass of products 

Arrhenius and Faraday

• proposed the idea of atoms that have charges —> ions

Crookes

• placed an iron cross in a cathode ray tube & observed the shadow of the cross

• proved that electrons were particles and not energy 

Thomson

• proposed the idea of subatomic particles (electrons and protons)

• atoms contained equal amount of electrons and protons

• placed a positive and negative plate around the cathode ray tube & observed the beam was attracted to the positive plate 

Rutherford

• shot alpha rays at gold foil

• proposed the idea of a nucleus where protons are surrounded by a cloud of negative electrons because some of the rays deflected back 

Chadwick

• proposed the idea of a neutron in the nucleus to account for the mass when compared to protons 

• found atoms of same element & diff mass called isotopes 

• all elements are relative to c-12

Radioactive

an element that emits radiation

Alpha decay

emits gamma radiation and helium

Beta decay

emits gamma radiation and electron

Gamma

emits gamma radiation

when are elements radioactive when looking at the neutron proton ration?

when n/p = 1.5 element is radiactive

intermolecular forces

bonds between atoms

what is a cation

metal loses valence electron to become stable —> positive ion (+)

what is a anion

non-metals gian electrons to be stable —> negative ion

when is covalent bonding found?

mollecular compounds (non-metal + non-metal)

what is covalent bonding?

non-metals share valence electrons in order to have a full shell to be stable

what are the 2 exeptions to the octect rule?

1. If the center atom has 3 energy levels (3rd row) or lower, they may have more than 8 electrons 

2. Certain atoms in the center such as B, Be can have less than 8 electrons (not full)

Why can the center atom on the 3rd energy level or lower have more than 8 electrons?

it has available d orbitals that are empty which allows for it to have more electrons.

What does a molecule with (-) mean?

add electron

What does a molecule with (+) mean?

remove electron

what does resonance mean?

• delocalized electrons in pi bonds moving positions

• structures that contain a double bond can have multiple ways of drawing

• EX CO3²- has 3 resonance 
  

How is a pi bond created?

unhybridized p-orbitals that are vertical to the bond axis overlap

what is bond length?

• distance between the 2 nuclei of the atoms involved in the bond

what does a longer bond length mean in terms of strength?

longer bond = weaker bond strength

what does a shorter bond length mean in terms of strength?

shorter bond = stronger bond strength

what is bond strength?

the amount of energy needed to break a bond

• pi bonds < sigma bonds

• multiple bonds > single bonds 

why was hybridization developed?

to explain the bonding and shape of molecular structures

how do you calculate electron domain?

sigma bonds + lone pairs of electrons

from what orbitals do you remove electrons?

s & p orbitals 

Who created VSPER theory?

Nyholm and Gillespe

why was VSPER theory created?

it was created to theorize why molecules have the shape they do

What does VSPER stand for?

Valence Shell Pair Electron Repulsion