atomic structure Flashcards
What are atoms made of?
1) protons
2) neutrons
3) electrons
What volume of an atom is occupied by its nucleus?
0.1%
What is the mass of an electron?
1/1836 the mass of a proton
What is the mass of an atom?
1) 1 atomic mass unit
2) 1/12 mass carbon-12
3) 1.67 x 10⁻²⁷ kg
4) 1 Dalton
What is the diameter of an atom?
10⁻¹⁰ m = 0.1 nm
What is the diameter of a nucleus?
10⁻¹⁵ m = 0.001 pm
isotope
atoms with same atomic number (Z) but different mass number (A)
Z
atomic number
A
mass number
Do all atoms have isotopes?
yes
What is the medical source of radioactivity?
cobalt-60
How is cobalt-60 made?
by bombarding cobalt-59 with neutrons
What are the 7 characteristic properties of atoms?
1) possess Mass
2) contain Electrons
3) Combine with one another
4) Have various properties
5) Attract one another
6) contain positive Nuclei
7) Occupy volume
frequency (v) =
number of waves per unit time
speed of light (c) =
frequency (v) x wavelength (λ)
photon
light that comes in a bundle / packet
energy (E) =
Planck’s constant (h) x frequency (v)
Planck’s constant
6.626 x 10⁻³⁴ J s
energy of an electron, E =
1/2mv²
wavelength of an electron, λ =
hv
Does an electron have magnetic properties?
yes
Heisenberg’s uncertainty principle
1) electrons have wave properties + so are always spread out rather than in one place
2) position of a moving electron cannot be defines
3) electrons are described as delocalised as their waves are spread out rather than pinpointed
4) the more accurately we know the position of an electron, the more uncertain we are about its motion
orbital
probable location of an electron
What 4 quantum numbers does an electron have?
1) principal quantum number (n)
2) azimuthal quantum number (l)
3) magnetic quantum number (mₗ)
4) spin quantum number (mₛ)
principal quantum number (n)
1) describes energy of orbital
2) positive integer
3) as n increases energy of electrons increase + orbital size increases
azimuthal quantum number (l)
1) describes angular momentum
2) describes shape of orbital
3) 0 or positive integer
magnetic quantum number (mₗ)
1) describes directionality
2) describes number of restricted orientations
3) integer between +l and -l
spin quantum number (mₛ)
1) describes spin direction
2) +1/2 or -1/2
Pauli exclusion principle
each electron in an atom has a unique set of quantum numbers
How many electrons can an orbital have?
2
Hund’s rule
the lowest energy configuration involving orbitals of equal energy is the one with the maximum number of electrons in the same spin orientation
