What is the problem asking?
Atomic mass of silicon = u = ?
Learn the theory at your own pace, try examples and test your new abilities with the quiz.
(Click the banner to open.)
The Atom Theory
The small dense core of an atom consisting of neutrons and protons. Neutrons and protons have approximately the same mass.
A neutral particle located in the nucleus of an atom.
A positively charged particle located in the nucleus of an atom.
A negatively charged particle located in the volume of space surrounding the nucleus of an atom.
Electrons and protons have charge that is equal and opposite, because of this we can say the relative charge in atomic units is one.
Particle | Charge (Coulombs) | Mass (kilograms) | Relative Charge | Mass (unified atomic mass units) |
---|---|---|---|---|
Proton | \(+1.6\) x \(10^{-19}\,C\) | \(1.673\) x \(10^{-27}\,kg\) | +1 | 1.0073 \(\,u\) |
Neutron | No Charge | \(1.675\) x \(10^{-27}\,kg\) | 0 | 1.0087 \(\,u\) |
Electron | \(-1.6\) x \(10^{-19}\,C\) | \(9.109\) x \(10^{-31}\,kg\) | -1 | \(5.4858\) x \(10^{-4}\,u\) |
\(\frac{1}{12}\) the mass of a carbon atom containing six protons and six neutrons.
Using this measurement, the mass of a proton and neutron is approximately \(1 \,u\).
The masses of all elements are defined using unified atomic mass units.
One or more atoms of the same type.
A one or two letter abbreviation assigned to each element.
The number of protons in the nucleus of an atom. The type of atom/element is determined by the number of protons.
The sum of the number of neutrons and protons in the nucleus of an atom.
28-14=14 neutrons
29-14=15 neutrons
30-14=16 neutrons
$$\sum_{n} \text{(fraction of isotope n) x (mass of isotope n)}$$
One mole of people is the Earth’s population multiplied by \(9\)x\(10^{13}\).
One mole of bricks is equivalent to \(2\)x\(10^{14}\) Great Walls of China.
One mole of sand is the entire Sahara Desert!
The mole is defined using the C-12 isotope.
One mole = number of atoms in exactly 12 g C-12.
12 g of C-12 = 1 mole of C-12 atoms = exactly \(6.02\)x\(10^{23}\) C-12 atoms
1 mole of carbon (C) \(6.02\)x\(10^{23}\) atoms
1 mole of sulfur (S) \(6.02\)x\(10^{23}\) atoms
1 mole of gold (Au) \(6.02\)x\(10^{23}\) atoms
One or more atoms that has lost an electron(s).
A main group METAL will LOSE electrons to form a CATION with the same number of electrons as the nearest noble gas.
One or more atoms that has gained an electron(s).
A main group NONMETAL will GAIN electrons to form an ANION with the same number of electrons as the nearest noble gas.
Ions are represented as the chemical symbol of the ion with the charge of the ion noted as a superscript to the right.
\(\text{X}^{\text{charge}}\)
Lithium ion \(=\text{Li}^{\text{+}}\), Oxygen ion \(=\text{O}^{2-}\)
Learn the theory at your own pace, try examples and test your new abilities with the quiz.
(Click the banner to open.)
Atomic Structure Theory
An electron's position described as a trajectory.
An electron's position described as a probability distribution.
Quantum Mechanical Model of an Atom. An electron's position described as a probability distribution.
Orbital’s size and energy level of an electron.
A whole number 1,2,3,4…..
n increases with an electron’s energy and distance from the nucleus.
Each level is called a shell.
The shape of an orbital.
0,1,2,3,…,n-1
Each value for l is a subshell
Each number value of l is assigned a letter s,p,d,f,g….
Orientation of orbital in 3D space.
Value= integer values from –l…l.
There are 2(l)+1 values of \(m_{l}\) for each value of l.
Values of (l) angular momentum | |
Number | Letter |
0 | s |
1 | p |
2 | d |
3 | f |
4 | g |
Electrons in a filled inner shell.
Electrons in the outermost shell (highest n value).
Example Carbon:
6 electrons = \(\stackrel{1s^{2}}{Core}\)
\(\stackrel{2s^{2}2p^{2}}{Valence}\)
An electronic configuration using a noble gas to represent the filled shells and only writing out the valence electrons.
Example Carbon:
6 electrons = \(\stackrel{He}{Core}\)
\(\stackrel{2s^{2}2p^{2}}{Valence}\)