What is Dalton’s Theory:
- 1. All matter consists of atoms
- 2. All atoms of a given atom are identical (false, isotopes)
- 3. The atoms of a given element are different from other elements and compounds
- 4. Atoms can not be created, destroyed or broken into smaller pieces (false)
What is Atomic Number: Z
- Is the number of protons in the atom.
- Is on the bottom left corner.
- For a neutral atom, number of protons = number of neutrons
What is The Mass Number: A
- The mass of the atom is concentrated in the nucleus, which contains protons and neutrons.
- Upper left corner of the atom
IWhat are isotopes? What are their properties?:
- Same proton, different neutron number
- Chemical properties are determined by number of electrons and are thus the same
- Physical properties vary
- -higher mass
- -higher density
- -higher melting and boiling points
- -slower rate of diffusion
Why are isotopes useful?
- Treating different kinds of cancer
- The sterilization of surgical instruments
- Nuclear power
- Crime detection
What are some Useful Isotopes:
- Cobalt 60
- Iodine 131
- Iodine 125
- carbon 12
How is Relative Atomic Mass calculated?;
(mass x relative abundance) of all isotopes/ 100
Explain Electron Arrangement
- The Bohr model is the basis
- An electron arrangement gives the number of electrons in each shell or orbit
- Main energy level, n, is called principal quantum number
- The shells are called principal quantum shells
- Each have a quantum number that increases as they go further from the nucleus
- Orbitals are the most probable positions of the electrons
- n=1 has an s orbital
- n=2 has an s and a p orbital
- n=3 has an s, p and a d orbital
- n=4 has an s, p, d, f orbital
- orbital = subshell
Explain s and p orbitals
- s has 1 box
- p has 3 boxes
- d has 5 boxes
- f has 7 boxes
- each box can hold two electrons
- The subshells fill in the order of increasing energy
What are the 3 ways to do electron configuration
- Full Electron Configuration
- Condensed/ Abbreviated Electron Configuration
- With a soygaz
- Orbital Diagram Representation
- With the boxes
What are some Exceptions to electron configuration?
: Cu, Cr 3d comes before 4s
What is Ionisation Energy?
- Ionization energy is the energy required to remove one mol of electrons from one mol of atoms in the gaseous state.
- Ionisation energy increases as we remove more electrons, bc it’s harder to remove electrons from an already positively charged atom
How does ionization energy change down the periodic table?
As the atom gets bigger and as we move down the periodic table, ionization energy decreases bc electrons further from the nucleus are easier to remove
How does ionization energy change from left to right on the periodic table?
The size of the atom decreases from left to right (same number of shells, more protons), thus the ionization energy increases
What is shielding? How does it affect ionization energy?
Shielding: inner electrons will shield electrons in lower shells by repelling them . The greater the shielding effect, the lower the ionization energy. More electrons = less ionization energy
What are some Exceptions to the trends regarding ionization energy on the periodic table?
- It’s easier to remove electrons from subshell p
- Be has a higher ionization energy than B
- 2. It’s easier to remove electrons from a full orbital
- N has a higher ionization energy than O
Electromagnetic Spectrum properties:
- Short wavelength, high frequency, high energy is the most dangerous
- Electromagnetic waves can travel through space or matter. The velocity of travel is related to its wavelength and its frequency.
- Tepe= crest
- Cukur= trough
What is frequency?
Frequency is the number of waves which pass a point in a second
How is speed of light calculated?
Speed of light: c = distance between successive crests x frequency
What is h?
h = Planck’s constant
What is E?
Electromagnetic Radiation, Energy of Photon = E
How is energy calculated?
- E= Planck’s constant x frequency
- E= h.c/distance between crests
Explain Absorption line spectrum
electron absorbs energy, goes to a higher energy level (dark)
Explain Emission line Spectrum
Electron loses or emits energy and goes down to a lower energy level (black lines on rainbow)
Explain Hydrogen Emission:
- Transitions to n=1 are UV radiation (highest energy)
- Transitions to n=2 are visible light
- Transitions to n=3 are infrared (lowest energy)
State from strongest electromagnetic radiation to weakest.
Gamma rays, X rays, UV, visible light, infrared, microwaves, radio waves
State from orbital with highest energy to lowest energy.
f, d, p, s
What is relative atomic mass?
The weighted mean mass of all the naturally occurring isotopes of an atom.