2.1 Flashcards
What are the relative masses of an electron, a proton, and a neutron?
R. mass of electron: 1/2000
R. mass of proton: 1
R. mass of proton: 1
Formula to find max. amount of electrons in each energy level
Each main energy level can hold a maximum of 2n^2 electrons.
“n” is the energy level
What main energy level has the lowest energy?
n=1 (the first one).
Order the sub-levels by the maximum number of electrons that each can hold in increasing order
s<p<d<f
Maximum number of electrons sub-level “s” can hold
s = 2 electrons
Maximum number of electrons sub-level “p” can hold
p = 6 electrons
Maximum number of electrons sub-level “d” can hold
d= 10 electrons
Maximum number of electrons sub-level “f” can hold
f = 14 electrons
What do “Z” and “A” symbolize in the periodic table?
Z= Number of protons
A= Number of nucleons (subatomic particles in the nucleus). In other words: protons+neutrons
Isotopes
Atoms with the same number of protons but a different number of neutrons
Examples: Carbon-12;Carbon-13;Carbon-14. Some times written as 12^C or 13^C
Properties of Isotopes
Isotopes of an element have different physical properties but identical chemical properties.
Bigger isotopes have a higher boiling point, melting point, and density (g mol^-1)
Relative abundance of an Isotope
Percentage of atoms with a specific mass number in a naturally occurring sample of the element.
Example:
Mg-24→r.a: 78.99%
Mg-25→r.a:10.00%
Mg-26→r.a: 11.01%
Formula to calculate relative atomic mass (Ar )
Ar= Isotope multiplied by their relative abundance + all the other isotopes (also multiplied by their respective relative abundances). Then this result is divided by 100.
Example:
How to calculate the relative abundance of EACH isotope of an element
Use the bigger isotope as X.
Use the second isotope as 100-X.
Example:
Anion
An atom or molecule that is negatively charged. More electrons than protons.
Example: Cl^2
Cation
An atom or molecule that is positively charged. Less electrons than protons.
Example: Na^+
