This quiz will cover isotopes, ions, and average atomic mass. You will have 20 minutes to take it in class. It will be all fill in the blank and calculation-based questions. BRING A PENCIL AND A CALCULATOR!
Mass number: Protons+neutrons
when given the mass number, subtract the amount of protons from the mass number (see atomic number), and what you’re left with is the amount of neutrons
Atomic number: protons
The larger number on the periodic table
Atomic mass: average of the relative amounts of each isotope
Electrons: Negatively charged particles, found outside of the nucleus of an atom
Protons: positively charged particles, found in the nucleus of an atom
Neutrons: uncharged particles, found in the nucleus of an atom
Neutral atoms: have the same amount of electrons and protons; neutrons differ
Isotopes: atoms of the same element with the same amount of protons and a differing amount of neutrons
the notation for this is has in subscript:
on the top left corner before the chemical symbol, the mass number
on the bottom left corner before the chemical symbol, the atomic number
Ex:
It can also be written with the element name, a dash, and then following that the mass number
Ex: Carbon-12
Ions:
there is not an equal amount of protons and electrons
if there are more protons than electrons, the charge is positive
Ex: Helium has a charge of +2. I know that it has 2 protons, but because it has a charge of +2, there are 2 more protons than electrons. Therefore, it has 0 electrons.
if there are more electrons than protons, the charge is negative
Ex: nitrogen has a charge of -3. I know that it has 7 protons, but because it has a charge of -3, there are 3 more electrons than protons. Therefore, there are 10 electrons.
Calculating average atomic mass (AAM): (atomic mass of isotope #1)(fractional abundance of isotope #1)+(atomic mass of isotope #2)(fractional abudnace of isotope #2)
fractional abundance is the percentage of a particular isotope in the total sample of atoms, written as a decimal
remember sig figs!!!
Significant figures
When multiplying/dividing sig figs, whichever # has the least amount of sig figs, you’ll round there
when adding/subtracting sig figs, line it up all the way. Whichever one is the shortest, go from there