Atomic Structure Flashcards
Isotopes
Atoms of the same element that differ in mass due to a different number of neutrons
John Dalton’s 4 Findings
- All atoms are composed of indivisible atoms
- All atoms of a given atom must be identical in every way
- Atoms of different elements must be different in some fundamental way
- Compounds are produced from a reaction between different atoms (elements)
Rutherford’s Experiment - 2 Observations
1) Most of the alpha particles passed through the gold foil
2) A few particles were deflected or back-scattered
Rutherford’s Experiment - 2 Conclusions
1) Most of the an atom is empty space
2) An atom contains a dense core with a positive charge
Proton
Location: Nucleus
Charge: +1
Mass: 1
Neutron
Location: Nucleus
Charge: 0
Mass: 1
Electron
Location: In orbitals outside the nucleus
Charge: -1
Mass: 0
Alpha particle
A charged helium nucleus
Beta particle
A high speed electron
Atomic number
The number of protons in an atom
Why is an atom electrically neutral?
The number of protons is equal to the number of electrons in an atom
Every element has a unique _____
Atomic number
Mass number
The number of protons plus the number of neutrons
Label parts: 11 5 B
Mass number: 11
Protons: 5
Atomic number: 5
Electrons: 5
Neutrons: 6
Word form: Boron - 11
Atomic mass
The weighted average of all naturally occurring isotopes of an element (decimal number)
How is the atomic mass of an element determined?
- Convert the percent abundances to a decimal (move decimal point two places to the left)
- Multiply the mass number by the converted percent abundance
- Add all the products
2 facts about atomic mass
1) Should be somewhere between the two original masses
2) Should be closest to the mass of the most abundant isotope
Bohr model description
Electrons revolve around the nucleus in one of seven shells or rings called potential energy levels (PELS). The rings correspond to rows or periods of the periodic table.
Compare the energy of electrons closest to the nucleus to the energy of electrons farthest from the nucleus
Close to nucleus = lowest energy
Farthest from nucleus = highest energy
What is the maximum number of electrons each PEL can hold?
1 - 2 electrons
2 - 8 electrons
3 - 18 electrons
4 to 7 - 32 electrons
What is the shortcoming of the Bohr model?
It is only a 2-D representation
Valence electrons
Electrons in the outermost PEL
Noble gases (group 18)
Odorless, colorless, nonflammable gases that are inert due to a complete octet
Inert
Do not react
If an ion is positively charged, it…
Lost electrons
If an ion is negatively charged, it…
Gained electrons
Isoelectronic
Have the same electronic configuration
Ground state electronic configuration
- Normal condition
- Electrons are in the lowest PELS
- Fill lower energy PEL first
Excited state electronic configuration
- Condition when an atom is bombarded by energy
- Electrons shift from low energy PELS to high energy PELS
How is the color produced from a Ne light?
Electrons shift from a high energy state to a lower energy state and release energy in the form of visible light
Line spectra
Produced from events and each element has a unique line spectra
Spectra/spectrum
A series of colors which forms when light is refracted
Spectroscope
A device that shows the component colors in a beam of light
Electromagnetic spectrum
Longest waves/lowest energy to shortest waves/highest energy: radio waves, microwaves, infrared, visible light, UV light, x-rays, gamma rays
Wave mechanical model
- Modern model of an atom
- Helps us locate where an electron is
Orbital
A region of space or volume where there is a high probability of finding an electron
Wave mechanical model chart
PEL - sublevel - number of orbitals - max number of electrons
1 - 1s - 1 orbital - 2 electrons
2 - 2s, 2p - 1 orbital + 3 orbitals = 4 orbitals - 2 electrons + 6 electrons = 8 electrons
3 - 3s, 3p, 3d - 1 orbital + 3 orbitals + 5 orbitals = 9 orbitals - 2 electrons + 6 electrons + 10 electrons = 18 electrons
4 - 4s, 4p, 4d, 4f - 1 orbital + 3 orbitals + 5 orbitals + 7 orbitals = 16 orbitals - 2 electrons + 6 electrons + 10 electrons + 14 electrons = 32 electrons
Hund’s Rule
Keep the electrons in separate orbital boxes first, then start to double them up
Lewis electron dot diagrams
Show the valence electrons that are lost, gained, or shared when forming a bond only
What characteristic allows elements in a group to share similar chemical properties?
Same number of valence electrons
