Atomic Number Number of Protons
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Atomic Number
Number of Protons
Mass Number
Number of Protons + Neutrons
12C
Left Superscript = mass number
6
12C
Left Subscript = atomic number
6
80Br
35
35
Atomic Number = ?
20Ne
20
10
Mass Number = ?
27Al
27
13
Mass Number = ?
40Ca
20
20
Atomic Number = ?
Isotope
Atoms of the same element with a different # of neutrons
Characteristics of Proton
Charge = +1, mass = 1 amu, location = inside nucleus
Characteristics of Neutron
Charge = 0, mass = 1 amu, location = inside nucleus
Characteristics of Electron
Charge = -1, mass = 1/1836 amu or 0.0005 amu, location =
outside nucleus
Ion
An atom that has gained or lost electrons & so carries
charge
Nucleons
Protons & Neutrons
atom
Smallest bit of an element that retains the properties of the
element.
atom
Electrically neutral. # of protons = # of electrons.
Charge
# protons - # electrons
# of neutrons
Mass number – atomic number
14C
8
6
# of neutrons = ?
9Be
5
4
# of neutrons = ?
40Ar
22
18
# of neutrons = ?
15N
8
7
# of neutrons = ?
24Mg
Right superscript = charge
12
2+
24Mg
10 electrons
12
2+
# of electrons?
86Rb
36 electrons
37
1+
# of electrons?
127Te
53 electrons
52
1-
# of electrons?
32S
18 electrons
16
2-
# of electrons?
Cation
Positive ion: atom lost electrons
Anion
Negative ion: atom gained electrons
Avg. Atomic Mass
Weighted avg. of masses of naturally occurring isotopes of
an element.
2 isotopes of Cl: 75% Cl-35 & 25% Cl-37.Calculate avg. atomic mass.
Avg. atomic mass = .75(35) + .25(37) = 35.5 amu
Dalton’s Model
Billiard Ball Model
Thomson’s Model
Plum Pudding Model
- --
- -+
+
+ ++
Rutherford’s Model
Nuclear Model
-
--
Rutherford’s Experiment
Source: http://www.dlt.ncssm.edu/TIGER/chem1.htm#atomic
Rutherford’s Experiment: Results
1) Most of the alpha particles went straight through. Most of the atom is empty space.
2) Some of the alpha particles were deflected back. The nucleus was tiny, but contained most of the mass of the atom.
Bohr’s Model
Planetary Model
Schrodinger’s Model
Modern or Quantum Mechanical Model
Source: http://www.dlt.ncssm.edu/TIGER/chem1.htm#atomic
Bohr Configuration
Ground state configurations found in reference tables.Cannot be predicted.
Bohr Configuration of Na = 2-8-1
2 electrons in energy level 18 electrons in energy level 21 electron in energy level 3
Bohr Diagram of Na
+11
Bohr Model
Electrons are restricted to specific orbits or shells or principle energy levels.Each shell holds a specific # of electrons.Each shell has a specific energy & radius.Energy of electron must match energy of shell.
Maximum Capacity of Bohr Levels
Shell # Max # of electrons
1
2
3
4
n
2
8
18
32
2n2
Ground State
Bohr modelEvery electron is in the lowest available orbit.
Excited State
Bohr modelAn electron has absorbed heat, light, or electrical energy and moved to a higher energy level.Unstable. Returns to ground state quickly by emitting a photon.
Continuous Spectrum
Spectrum produced by holding a prism in sunlight. Contains light at every wavelength.
Bright Line Spectrum
Visible light produced by electrons in atom returning to ground state: light of only a few wavelengths is present.
Each element has a unique bright line spectrum. Used to identify elements.
Wavelengths of bright lines correspond to difference between energy levels.
Source: http://www.dlt.ncssm.edu/TIGER/chem1.htm#atomic
Absorbtion of Energy
h Ground state
Excited state
E1
E2
E3
Emission of Energy
h
Ground state
Excited state
E1
E2
E3
Orbital
Modern ModelRegion of space that holds 2 electrons.Has a specific energy. Shapes vary.
Related Documents
