1.2 The nuclear atom

Question 1

nucleon

Answer 1

protons and neutrons

Question 1

The mass number

Answer 1

proton plus the number of neutrons in the nucleus of the atom

Question 2

line spectrum (hydrogen atom)

Answer 2

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

Question 3

continuous spectrum

Answer 3

showing an unbroken sequence of all wavelength/colors of light such as the spectrum of visible light.

Question 4

a) define hydrogen emssion spectrum
b)describe how the emission spectrum of an element arises

Answer 4

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

Question 5

ionization energy

Answer 5

the energy required to remove one electron from each atom in one mole of gaseous atom under standard condition

• must put gaseous symbol

Question 6

atomic radius

Answer 6

the distance between the 2 nuclei in a diatomic molecule or between the center of the nucleus and outermost shell

Question 7

electronegativity

Answer 7

ability of an atom to attract a shard pair of electron in a covalent bond

Question 8

electron affinity

Answer 8

the energy released when 1 mol of electron

Question 9

cation

Answer 9

positive ion by loosing electrons

Question 10

anion

Answer 10

negative ion by gaining electron

Question 11

Calculating number of protons and neutrons

Answer 11

-Atomic Number: Number of protons
-Mass Number: Number of protons and neutrons
-Number of electrons = atomic number – charge

Question 12

Mass spectrometer

Answer 12

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.

Question 13

How can relative atomic mass of a sample be determined from mass spectrum

Answer 13

a. Multiply relative intensity by m/z value of isotopes
b. Find frequency of each isotopes
c. Calculatae the weighted average

Question 14

Gold foil experiment

Answer 14

Positive alpha particles hit positive particles of the gold-foil. Prove that atoms are empty space with tiny dense positively charged nucleus.

Question 15

State chemical and physical properties of isotopes

Answer 15

• 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.

Question 16

radioactive isotopes

Answer 16

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

Question 17

What are the impacts of radioactive isotopes

Answer 17

cell destruction, cancer, genetic mutation

Question 18

What does the horizontal line of M/Z value on mass spectra represent

Answer 18

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.

Question 19

atomic mass formula

Answer 19

Question 20

atomic number

Answer 20

the number of protons in the nucleus. Since atoms are electrically neutral, the number of protons is also equal to the number of electrons

Question 21

Bohr model

Answer 21

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)

Question 22

What did the emission spectrum prove?

Answer 22

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

Question 23

Balmer series (visible light)

Answer 23

lines of the hydrogen atom that result from electron
transitions from higher levels down to the energy where energy level where n=2

Question 24

Ultraviolet light (Lyman series)

Answer 24

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

Question 25

Infrared light (Paschen)

Answer 25

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

Question 26

properties of wave

Answer 26

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

Question 27

first ionisation energy

Answer 27

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

Question 28

wavelength

Answer 28

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.

Question 29

Give an equation for the conversion of a wavelength of light into its frequency

Answer 29

speed of light equation

Question 30

Equation for finding ionization energy/photon energy by using speed of light and planks constant

Answer 30

Question 31

photon

Answer 31

• photon -> single wavelength/energy released as electron transitions form higher to lower energy level

Question 32

State the energy transition for the following

1) purple
2)blue
3)green
4)red

Answer 32

1) n=5~n=2
2)n=4~n=2
3)n=3~n=2
4)n=2~n=2

Question 32

Flame experiment

Answer 32

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

Question 33

Limitations to Bohr model

Answer 33

Question 34

State number of electrons each sub levels can hold

Answer 34

Each main level can hold a maximum of 2n2 electrons.

• s :2 electrons
  -p :6 electrons.
• d :10 electrons.
• f :14 electrons.

Question 35

emission spectra

Answer 35

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)

Question 36

Color wheel

Answer 36

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​

Question 37

Writing electron configuration

Answer 37

When the transition metal atoms form ions: the 4s orbital is filled first before 3d, but is removed first before 3d

Question 38

Distinguish between main energy shell, sublevel, and orbital

Answer 38

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

Question 39

Describe how the first ionization energy (convergence) of hydrogen can be obstained form its emission spectrum

Answer 39

1. 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

Question 40

Line of convergnce

Answer 40

series become closer together as their wavelength decreases (as their frequency and energy increases). Accounts for first ionization energy.

Question 41

Give an equation for calculating energy for packet of photon

Answer 41

• 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)

Question 42

conversion of nanometer to meter

Answer 42

Question 43

what appartus is used to measure the relative isotopes

Answer 43

mass spectormeter