Unt 1 - Atomic Structure Flashcards
What year did Dalton create the Billard ball model?
1809
What was the limitation of Dalton’s Billard ball model
It could not explain why atoms of elements combine in the way they do
What was Thompson’s model and what year was it created
1887,
A chocolate chip cookie
Electrons in a positive sphere
What and who disproved Thompson’?
Rutherford with the gold foil experiment
What year was Rutherford’s diagram created and what did it look like?
1909
Positive nucleus, electrons floating around
What were the limitations on Rutherford’s theory?
-A nucleus of only positive charges would repel
- didn’t account for entire weight of an atom
- Electrons in motion should continuously give off radiation (light) and lose energy, atoms would implode
What did Bohr’s diagram look like and what year was it created?
1913,
Orbits of electrons and energy levels
Limitations of Bohr diagram
-Could only explain single electron atoms (H, He, Li etc)
Why did Bohr disprove Rutherford?
Energy emitted should be continuous but it is not
Within energy level electrons do not emit energy
Electrons change level by absorbing or emitting energy
Who discovered neutrons?
James Chadwick, 1932
Who discovered protons?
Rutherford, 1914
Who discovered isotopes?
Frederick Soddy, 1913
What is a photon?
A particle of light
What a quantum of light energy is called
What is a Quantum?
A packet of energy
Plank
What is a continuous spectrum?
The spectrum that consists of a continuum of wavelengths
What is Emission spectrum?
The spectrum of frequencies of electromagnetic radiation emitted due to an electron making a transition from high energy state to a lower energy state
What is an absorption spectrum?
The spectrum of frequencies of electromagnetic radiation absorbed due to an electron making a transition from a low energy state to a higher energy state
In an orbit, are electrons a fixed or variable difference from the nucleus?
Fixed distance
Are orbitals 2D or 3D?
3D
How many electrons are there per orbital?
2
How many electrons in an orbit?
2, 8 or 18
An orbital with 1 orbital orientation, up to 2 electrons that is in all energy levels is called…
S-shape
An orbital with 3 orbital orientations, up to 6 electrons that is in energy level 2 and up is called…
P-shape
An orbital with 5 orbital orientations, up to 10 electrons and in energy level 3 and up is called…
D-shape
An orbital with 7 orbital orientations, up to 14 electrons and is in energy level 4 and up is called…
F-shape
What is the right order when writing an energy level diagram?
1s, 2s, 2p, 3s, 3p, 4s, 4d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 5f, 6d
What can the row an element is in on the periodic table tell you about its energy level diagram?
Energy level
What form of diagram/ configuration do you draw the direction of spin each electron has?
Energy level diagram
What is this an example of?
1s^2, 2s^2, 2p^6, 3s^2, 3p^1
Complete electron configuration
What is this an example of?
[Ne] 3s^2, 3p^1
Condensed electron configuration
What does VSEPR stand for?
Valence Shell Electron Pairs Repel
What is VSEPR theory?
Pairs of electrons in valence shell stay as far away as possible
What is a Hybrid orbital?
Atomic orbitals overlap to form new orbital containing a pair of electrons of opposite spin
Which VSPER shapes are always non-polar?
Linear
Linear
Trigonal Planar
Tetrahedral
What VSEPR shapes may be polar?
Bent/Angular
Bent/Angular
Pyramidal
What EN difference does a bond need to be polar?
0.4-1.8
EN difference of a covalent bond?
<0.4
EN difference of an ionic bond
> 1.8
EN difference of an ionic bond
> 1.8
Give 2examples if intramolecular forces
Ionic and Covalent
What is an intramolecular force?
Forces between atoms and ions within a molecule
Which is stronger, intermolecular forces or intramolecular forces?
Intramolecular
What is another name for intermolecular forces?
Van der Waals forces
What is an intermolecular force?
Attractive forces between molecules
What are weaker, intermolecular forces or intramolecular forces?
Intermolecular forces
What are 3 examples of intermolecular forces?
H-bonds, dipole-dipole, London dispersion forces
Does it take less energy to melt a substance or break it down into separate elements?
Melt a substance
What is a dipole-dipole force
Attraction between oppositely charged ends of polar molecules
Which intermolecular force is the weakest?
London dispersion
What is a London dispersion force?
Nucleus attracts electrons from neighbouring molecules
Present in all molecules, important in non-polar molecules
At moderate distance attraction can be stronger than the repulsion of electrons
The higher amount of electrons the ________ the London force
Stronger
The _________ amount of electrons the weaker the London force
Lower
What size of molecules have low boiling points
Small neutral molecules
Do big molecules have high or low boiling points?
High
Molecules with the approximate same London forces have the same amount of _______
Electrons
The more polar a molecule and the stronger the dipole-dipole attraction the ___________
Higher the boiling point
What is the strongest intermolecular force?
Hydrogen bonds
What is a hydrogen bond?
Strong dipole-dipole force
H-bonds are _____%-______% as strong as covalent bonds
5%-10%
What elements does hydrogen bond with in H-bonds?
Fluorine
Oxygen
Nitrogen
Rank the intermolecular forces from weakest to strongest
London dispersion
Dipole-dipole
H-bonds
The higher the force the higher the __________+__________
Melting point and boiling point
What is an ion dipole?
Ion and polar molecule
Ex. NaCl separating into ions when surrounded by water
Ion induced dipole,
Ex O2 sticks to hemoglobin in bloodstream
Ion close to non polar molecule induced temp dipole
Dipole induced dipole
charge on polar molecule induces dipole on non-polar molecule
which intermolecular force has the highest vapour pressure and Wich has the lowest
HIghest: london
Lowest: H-bonds
What is an ionic crystal?
A non-metal + metal with very strong ionic bonds in all three planes
What are the characteristics of ionic crystals?
- High melting point and boiling point
- An electrolyte in solution
- High solubility
- Hard and brittle
How do metallic crystals differ from ionic crystals?
They have weaker electrostatic attraction and positive core with mobile electrons
List the properties of metallic crystals.
- Variable melting and boiling points
- Electrolyte
- Not soluble in water
- Lustrous
- Malleable
- Ductile
- Hard
- Dense
- Conducts heat
What defines a molecular crystal?
Non-metals with weak intermolecular attraction
What are the properties of molecular crystals?
- Low melting and boiling points
- Not an electrolyte
- Soft
What characterizes a covalent network crystal?
Covalent bonds between molecules
List the properties of covalent network crystals.
- Very high melting and boiling points
- Not an electrolyte (except graphite)
- Not soluble in water
- Hard
- Brittle
What is an amorphous solid?
A solid with various bonding that melts over a range of temperatures
What are the characteristics of amorphous solids?
- An electrolyte for metallic variants
- Very soluble in water
- Composed of molecules not arranged in an orderly crystalline structure
What is notable about graphite’s bonds compared to diamonds?
The bonds in graphite are stronger than those in diamonds
What are the properties of graphite?
- Conductivity
- Resistant to chemical reactions
How much stronger is graphene compared to diamond?
40x stronger than diamond
What makes graphene superior to graphite?
Significantly superior properties
What experiment disproved Thompson’s model of the atom?
Gold foil experiment
Conducted by Rutherford in 1909.
Who conducted the gold foil experiment?
Rutherford
The experiment took place in 1909.
What particles were used in the gold foil experiment?
Alpha particles
These particles were shot at thin gold foil.
What unexpected result occurred during the gold foil experiment?
1 in 1800 alpha particles deflected significantly
This was not expected based on Thompson’s model.
What conclusion was drawn from the gold foil experiment?
Atom is mostly empty space with a concentrated charge at the center, the nucleus
This led to a new understanding of atomic structure.
What limitation of the gold foil experiment is mentioned?
Only positive nucleus would repel
It did not account for the entire weight of an atom.
What is another limitation regarding electrons mentioned in the context of the gold foil experiment?
Electrons in motion should continuously give off radiation (light) and lose energy so atoms would implode
This was not addressed in the experiment.
What concept did de Broglie introduce regarding electrons?
Electrons as waves
De Broglie’s theory states that electrons do not follow specific orbits but exhibit wave-like behavior.
What condition must the orbital circumference meet according to de Broglie’s theory?
It needs to fit whole waves, not half ones
This means that only orbits of certain sizes are allowed.
What does Heisenberg’s uncertainty principle state?
It is impossible to predict both the position and momentum of an electron with certainty
This principle arises due to the wave nature of matter.
What significant equation did Schrödinger derive?
An equation that tells the probability that an electron is at a particular point
This equation is fundamental in quantum mechanics.
What replaced Bohr’s orbits in Schrödinger’s model?
Orbitals
Orbitals represent regions of probable location for electrons rather than fixed paths.
How are electron clouds represented in quantum mechanics?
They can be drawn to show regions where electrons are likely to be found
This visualization helps in understanding the behavior of electrons.
What is a characteristic of Bohr’s orbits?
They are 2D
In Bohr’s model, electrons are fixed at a distance from the nucleus.
What is the maximum number of electrons that can occupy a Bohr orbit?
2, 8 or 18 electrons per orbit
These numbers represent the capacity of different orbits in Bohr’s model.
What is a characteristic of orbitals in quantum mechanics?
They are 3D
Orbitals allow for variable distances of electrons from the nucleus.
What is the maximum number of electrons that can occupy a single orbital?
2 electrons per orbital
This is based on the Pauli exclusion principle.
