1.2 The nuclear atom Flashcards
nucleon
protons and neutrons
The mass number
proton plus the number of neutrons in the nucleus of the atom
line spectrum (hydrogen atom)
only certain wavelengths/colors of light becasue it is produced by excited atoms and ions as they fall back from an energy level higher than n=2 to n=2 in the visible regions
continuous spectrum
showing an unbroken sequence of all wavelength/colors of light such as the spectrum of visible light.
a) define hydrogen emssion spectrum
b)describe how the emission spectrum of an element arises
Consist of 4 series of lines. photons emitted from atoms as excited electrons go from a higher energy level to a lower energy level. Electron transition or the distance between two energy levels corresponds to discrete/certain colors/wavelength/frequencies of visible light.
Multiple photons are emitted by a sinlge atom as the electron moves between different energy levels forming a complete emission spectrum
ionization energy
the energy required to remove one electron from each atom in one mole of gaseous atom under standard condition
- must put gaseous symbol
atomic radius
the distance between the 2 nuclei in a diatomic molecule or between the center of the nucleus and outermost shell
electronegativity
ability of an atom to attract a shard pair of electron in a covalent bond
electron affinity
the energy released when 1 mol of electron
cation
positive ion by loosing electrons
anion
negative ion by gaining electron
Calculating number of protons and neutrons
-Atomic Number: Number of protons
-Mass Number: Number of protons and neutrons
-Number of electrons = atomic number – charge
Mass spectrometer
A mass spectrometer separates individual isotopes from a sample of atoms and determines the mass of each isotope. Magnetic field makes different deflections depending on mass and average percentage abundance. # hits in the detector quantifies and shows relative percentage isotopes. Carbon isotope 12C was chosen as a standard, and it was given a relative mass of exactly 12.
How can relative atomic mass of a sample be determined from mass spectrum
a. Multiply relative intensity by m/z value of isotopes
b. Find frequency of each isotopes
c. Calculatae the weighted average
Gold foil experiment
Positive alpha particles hit positive particles of the gold-foil. Prove that atoms are empty space with tiny dense positively charged nucleus.
State chemical and physical properties of isotopes
- Chemical properties depend on the outer shell of electrons. Since isotopes still have the same number of electrons, these
properties will remain the same - Physical properties depend on their nuclei. Since the number of neutrons changes, properties such as density, rate of diffusion, melting, and boiling change. The mass will also change.
radioactive isotopes
Force inside the nucleus called the binding energy holds protons together. When isotopes have more/less neutrons (radioactive isotopes) they undergo radioactive decay by releasing nucleons and alpha particles (energy) to reach a stable state.
After half life, radioactive isotopes have decayed
What are the impacts of radioactive isotopes
cell destruction, cancer, genetic mutation
What does the horizontal line of M/Z value on mass spectra represent
The horizontal axis shows the mass/charge ratio of the different ions on the carbon- 12 scale, which in most cases can be considered equivalent to their mass. The percentage abundance of the ions is shown on the vertical scale.
atomic mass formula
atomic number
the number of protons in the nucleus. Since atoms are electrically neutral, the number of protons is also equal to the number of electrons
Bohr model
1)higher the energy level the further away the electron is from the nucleus, and the higher the energy
2) Energy in discrete energy levels
3) electrons absorb energy they move up to a higher energy level. This is called the excited state. When the electron returns to a lower energy (ground state) level. They emit photons or energy.
4) energy level coverage/get closer with distance from the nucleus (ionization energy)
What did the emission spectrum prove?
The line emission spectrum of hydrogen provides evidence for the existence of electrons in discrete energy levels
The energy of the lines on the emission spectrum of hydrogen corresponds to the difference in energies between energy
levels
Balmer series (visible light)
lines of the hydrogen atom that result from electron
transitions from higher levels down to the energy where energy level where n=2
Ultraviolet light (Lyman series)
lines of the hydrogen atom that result from electron
transitions from higher levels down to the energy where energy level where n=1
*highest energy difference
*higher energy/photon
*shorter wavelength
*less frequency
Infrared light (Paschen)
lines of the hydrogen atom that result from electron
transitions from higher levels down to the energy where energy level where n=3
*lowest energy difference
*lower energy/photon
*longer wavelength
*lower frequency
properties of wave
a) the speed of the wave is constant (C=3.0x10^8ms^-1) but the wavelength is different. Wavelength is the amount of energy released during electron transition
b)waves have amplitude
c)waves gives of electrical property and magnetic property
first ionisation energy
minimum energy needed to remove one mole of electrons from one mole of gaseous atoms in their ground state
𝑯(𝒈) → 𝑯+(𝒈)+𝒆−
n=∞ energy level
wavelength
The distance between two successive crests (or troughs) is called the wavelength ( λ). The frequency (f) of the wave is the number of waves that pass a point in one second.
The wavelength and frequency are related by the equation c= fλ where c is the speed of light.
Give an equation for the conversion of a wavelength of light into its frequency
speed of light equation
Equation for finding ionization energy/photon energy by using speed of light and planks constant
photon
- photon -> single wavelength/energy released as electron transitions form higher to lower energy level
State the energy transition for the following
1) purple
2)blue
3)green
4)red
1) n=5~n=2
2)n=4~n=2
3)n=3~n=2
4)n=2~n=2
Flame experiment
Atoms of different element give distinctive color (discrete energy level) as promoted electron move from higher to lower energy level. Energy difference between levels are different.
Color not in the visible light are mixture of frequency of element’s color
Limitations to Bohr model
State number of electrons each sub levels can hold
Each main level can hold a maximum of 2n2 electrons.
- s :2 electrons
-p :6 electrons. - d :10 electrons.
- f :14 electrons.
emission spectra
when electrons are excited to a higher energy level, and then return to a lower energy level, they release a photon of a specific energy, as shown by a specific frequency of light.
Can be either continuous spectra or line spectra (ex. hydrogen)
Color wheel
Use c=vλ and E=hv to find λ, then use the color wheel to determine what color light is emitted
Make sure to convert m to nm when using the IB color wheel
Writing electron configuration
When the transition metal atoms form ions: the 4s orbital is filled first before 3d, but is removed first before 3d
Distinguish between main energy shell, sublevel, and orbital
Oribtal:2 electrons
subshell: number of orbital ➡ s (2subshell) ,p (3 subshell) ,d (6 subshell) ,f( 7subshell)
shell ➡ energy levels: degenerate orbitals belonging in the same distance from the nucleus
Describe how the first ionization energy (convergence) of hydrogen can be obstained form its emission spectrum
- Step 1: determine the frequency of line/phonton at the convergence limit in the highest frequenxy/ lyman n=1
Step 2: calculate energy, in J, of one photon by using the formula 𝐸 (ionization energy) = 𝜆𝑣
Step 3:mutliply the energy of one photon by Avogadro’s number to get a value in Jmol-1
Line of convergnce
series become closer together as their wavelength decreases (as their frequency and energy increases). Accounts for first ionization energy.
Give an equation for calculating energy for packet of photon
- For ionization energy from E=hf, need to multiply by Avogadro’s constant and then divide by 1000 e=hf gives only energy of one electron in J and we need kjmol-1)
conversion of nanometer to meter
what appartus is used to measure the relative isotopes
mass spectormeter
