1. Chapter 2 Notes
The mass of an atom is concentrated in its minute, positively charged nucleus.
Chapter 2.1: The nuclear atom

2. Important Terms for this Section
Quantum Theory Elements Atoms Compounds Molecules Sub-atomic particles Electrons Nucleons: Neutrons Protons
Mass number
Atomic number
Isotope
Ion
Cation
Anion
Mass spectrometer
mass spectrum

3. Quantum theory
Please shorthand note the following: A theory based on the principle that matter and energy have the properties of both particles and waves, created to explain the radiation of energy from a blackbody, the photoelectric effect, and the Bohr theory, and now used to account for a wide range of physical phenomena, including the existence of discrete packets of energy and matter, the uncertainty principle, and the exclusion principle. Ex: theory re: matter and E have particle and wave props. Created explain  rad of E from blackbody photoele. Effect, Bohr thry uncert princ exclusion princ.

4. elements
Substance that cannot be broken down into simpler substances by a chemical reaction Example: different elements have different chemical properties, but the same kind of element may have different physical properties but have similar chemical properties (such as gold dust vs. gold foil)

5. Dalton: Solid Sphere model of the atom
All matter is composed of tiny indivisible particles called atoms Atoms cannot be created or destroyed Atoms of the same element are alike in every way Atoms of different elements are different Atoms can combine together in small numbers to form molecules Result = Solid Sphere Model This helps us understand how elements react to form compounds (balanced reactions and bonding)

6. J.J. Thompson: Plum pudding model
Discovered there are negative charges in the atom = electrons Negative charges embedded in a positive core

7. Summarized Experiment
Voltage
Cathode
(-)
anode
(+)
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Empty glass tube (vacuum) connected to a metal cathode and anode.
High voltage is applied to the tube.
This caused the atoms in the cathode to get excited.
Electrons stream off the cathode, producing a cathode ray.
The cathode ray traveled toward the anode

8. Summarized Experiment
Voltage -
Cathode
(-)
anode
(+)
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When a negative charge was brought toward the cathode ray, it caused the cathode ray to move away from the negative charge.

9. Summarized Experiment
Voltage +
Cathode
(-)
anode
(+)
Click here
When a positive charge was brought toward the cathode ray, it caused the cathode ray to move toward the positive charge.

10. Ernest Rutherford: Nuclear Model
Gold foil experiment Results = Positively charged nucleus in center of atom Electrons moving around nucleus at a distance

11. Atoms gain E = e- move way from nucleus (higher E level) Atoms lose E = e- move toward nucleus (lower E level) & release light Electrostatic force of attraction between p+ and e- prevents e- from leaving atom Neutrons are needed to stabilize larger atoms
Energy Added
Energy Released e-
The resulting hydrogen atoms are excited; that is, they contain excess energy, which they release by emitting light of various wavelengths to produced emission spectrum of the hydrogen atom. e-
Absorbs energy
Releases energy

12. Atomic and mass numbers
This should be strictly review... I shouldn’t need to have a long and detailed slide for this, right? NOTE: sometimes mass number, A, is also referred to as the nucleon number

13. Isotopes
Isotopes: change in number of neutrons PROTONS DO NOT CHANGE!!! Ex: Carbon-12 and Carbon-14 Chemical properties of isotopes are the same Physical properties can change among isotopes of an atom - boiling and melting points are higher for isotopes of heavier mass as they move more slowly (think King Bowser on Mario Kart) Some isotopes can have radioactive properties: Ex: Hydrogen, Deuterium, Tritium Draw the atomic symbols for each one. List the number of protons and neutrons for each one.

14. ions
Ions: Change in the number of electrons results in a charged particle Cations: positively charged ions (loses electrons) Anions: negatively charges ions (gains electrons) PROTONS DO NOT CHANGE!!!

15. Mass spectrometer
Used to measure the mass of individual atoms Hydrogen mass = 1.67 x g & Carbon mass = 1.99 x g And all other masses are in the ranges of – what does this mean to you? Nothing probably! So, using Carbon-12 as a standard - Carbon is given the relative mass of 12

16. Mass spectra
These are the images/graphs that come off the analysis of the MS Mass to charge ratio m/z compared to the relative intensity Calculating relative atomic mass: - total mass of atoms = (%*m/z) + (%*m/z) + etc. - total mass/number of atoms = relative average mass
0.0309
0.0479