Atomic Structure Flashcards
What did Democritus contribute?
Elements are made up of small invisible particles. There is a point where matter can no longer be broken down
What did Empedocles contribute?
Fire, air, water, earth.
492-375
What did dalton contribute?
Atoms are solid particles
What did JJ Thompson contribute?
Discovered the electron, the atom is divisible. The atom is a positive sphere with negative electrons imbedded throughout, balancing to neutral. Most of mass is positive.
Who used a cathode ray tube and a beam with negatively charged particles?
JJ Thompson
What did Rutherford contribute?
Discovered the nucleus. Atom is mostly empty space. Hard core in the middle is the nucleus, most of the mass.
Who shot alpha particles at gold foil?
Rutherford
What did Bohr contribute?
Electrons in fixed shells/energy levels. Electrons are capable of absorbing and emitting energy. The energy of an electron is quantized.
Who used flame tests?
Bohr
What is quantum?
A discrete quantity of energy proportional to the frequency of the radiation it represents.
What does discrete mean?
Comes in packets or bundles
What does continuous mean?
All values are allowed
What did Max Planck do?
Developed a theory that all energy is quantized and not continuous as one believed.
What is the formula Max Planck developed?
E=he
Amount of energy=plan is constant X frequency
What is plancks constant?
H= 6.63 X (10)-34 J.S
What is the speed of light?
3 X (10)8 m/s
What is the universal wave equation?
C=f^
What is a nanometer?
1nm=1 X 10^9
What is light?
Electromagnetic radiation that travels through space or matter in wave like as illustrious. Sometimes it behaves like a wave, others like a particle
What is ground state?
Lowest possible energy level and electron can be at
What is excited state?
An energy level higher than the ground state. Electrons absorb or emit light energy when they jump from one energy level to another
What is emitted light?
Depends on how big the jump between orbits was. The bigger the jump, the higher the energy. Light emitted produces a unique emission spectrum. Colour seen is a result of different wavelengths of light emitted when the electrons fall down steps to their ground state.
⬆️ absorb
⬇️release
What is the uncertainty principle? Who was it developed by?
We can not know both the position and momentum of a particle at a given time. Makes it impossible to plot and orbit for an electron. The probably location of an electron is based on how much energy the electron has.
Developed by Werner Heisenberg
What are wave properties of matter?
Particles may behave as both particles and waves. (Wave-particle dualities)
Wavelength= h/mv
What did Erwin Schrodinger contribute?
His equations indicate the probability of where an electron may be found.
What is an electron cloud/orbital?
The space in an atom where an electron is likely to be found
What is the principle quantum number?
Energy level. Represented by n. Values can have all integers.
What is the angular momentum quantum number?
Shape. Represented by l.
Values can have:
S p d f g
0 1 2 3 4
What is the magnetic quantum number?
Orientation in space. Represented by ml. Values can have from -l to +l
What is the electron spin number?
Spin. Represented by ms. Values can have +1/2 (spin up) or -1/2 (spin down)
What is atomic orbital?
A region in space in which there is a high probability of finding an electron
What is the quantum mechanic model?
Electrons are located in specific energy levels. There is no exact path around the nucleus. The model estimates the probability of finding an electron in a certain position.
What is the aufbau diagram?
1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 5g
What is the Pauli exclusion principle?
No 2 electrons in an atom can have the same set of 4 quantum numbers. This means no atomic orbital can contain more than 2 electrons.
What is hund’s rule?
The most stable arrangement of electrons is that with the maximum number of unpaired electrons, all with the same spin direction.
What is atomic radius?
The distance from the nucleus to the outermost region of the atom. Increases down a family, decreases across a period
What is ionization energy?
The amount of energy required to remove a cal me electron. Decreases down a family. Increases across a period.
What is electron affinity?
The amount of energy released when an electron is added to an atom. Decreases down a family. Increases across a period.
What is electronegativity?
Tendency of an atom to attract a pair of electrons within a bond. Decreases down a family. Increases across a period.
What is ionic bonding?
Transfer of electrons from metals to non-metals. Electrostatic attraction between cation and anion.
EN >_ 1.7
What is non-polar covalent?
Equal sharing of electrons between atoms.
EN<_0.5
What is polar covalent?
Unequal sharing of electrons between atoms.
0.5 < EN < 1.7
What are characteristics of polyatomic ions?
Central atom is most electronegative
Oxygen atoms surround central atom
Hydrogen usually bonded to oxygen
Choose the most symmetrical arrangement
What is resonance?
The structure must be drawn multiple times to show the double bond could occur in various places
What is a sigma bond?
The first bond made with any other atom. Capable of rotation.
What is a Pi bond?
Any second or third bond made with any other atom. Made from left over p orbitals . Not capable of rotation.
What is valence bond theory?
Proposes that overlapping of atomic valence orbitals result in forming a bond between 2 atoms. Specifically, covalent bonds are formed by the overlap of valence atomic orbitals
What is hybridization?
When atoms bond, their atomic orbitals (s,p,d) mix together to create hybrids or combinations of atomic orbitals. These hybridized molecular orbitals have different shapes and energy levels
What are intramolecular forces?
The force of attraction within atoms in a molecule
What are intermolecular forces?
The force of attraction and repulsion between molecules.
What are the three intermolecular forces?
Dipole dipole
London forces
Hydrogen bonding
What are dipole-dipole forces?
Attractive forces that exist between polar molecules. Partial charges in the molecule are created due to unequal sharing of electrons in the bond (permanent dipoles). These are stronger than London forces, but London forces are still present.
What are London forces?
Present in all molecules. Simultaneous attraction between nucleus of one molecule and electrons in an adjacent molecule due to temporary dipoles. Weakest of all intermolecular forces.
What is hydrogen bonding?
Dipole-dipole interactions experiences when H is bonded to highly electronegative atoms N O F. Hydrogen is attracted to the lone pair. Because H atom is so small, it can get very close, creating a shorter bond. Short = strong. Strongest of all intermolecular forces.
What are bonds?
When bonds are created the potential energy in the system decreases. The bond formation at this lower energy state increases the stability of the bond