Session 6 help

Subatomic particles

These particles in different combinations make up the different types of elements.

Proton p+

1 amu. In the nucleus.

it attracts electrons and determines type of element

Neutron n0

1 amu. in the nucleus.

stabilizes protons and determines type of isotope.

Electrons e-

0 amu. Found around nucleus. does chemical reactions, and determines type of ion.

Isotopes

Element types can come with different numbers of neutrons and still be the same type of element they vary in mass.

Weighted mass

What you have for mass on the periodic table is a weighted average mass of the naturally occurring isotopes of that element.

Neutral element

has the same number of protons and electrons so if you add the positive charges (from protons) and negative charges (from electrons) you get 0.

Ions

Contain a different number of protons and electrons resulting in an overall charge to the atom.

Cations

Have more protons than electrons, leading to an overall positive charge on the atom.

Anions

Have more electrons than protons leading to an overall negative charge on the atom.

Atomic Mass/ Mass Number

the protons and neutrons added together

Atomic Number

The number in the upper right of your periodic table. It counts up as you move across the rows. This number indicates the element type and the number of protons in the element.

Ionic charge

Indicates the number of electrons above (negative charge) or below (positive charge) neutral. Is written as a superscript after the element symbol.

Scientific notation

How to write big or small numbers.

Isotope Formula - x yZ, Isotopes are written differently than the symbols are on the periodic table. The superscript x is the mass number (the protons + the neutrons), the y is the atomic number (the number of protons) this one is not always written in since you can look up the symbol to find the atomic number on your periodic table. Z is the element symbol and will be one that matches something on the periodic table. If it isn’t given to you, use the atomic number or the number of protons (same number) to look up the symbol on the periodic table.

^x_yz.

Protons = Atomic number

Neutrons = Atomic mass – Atomic number (then round to the nearest whole number since we don’t have partial neutrons.)

Electrons = atomic number – charge (remember – a minus means to add) So for example Ca 2+has 20 – 2 = 18 electrons, N 3-has 7-(-3)= 7+3 = 10 electrons. If there is no charge then the electrons equal the atomic number.

Isotope mass formula = Protons + Neutrons

Atomic mass formula =  isotope mass x (isotope percent/100) (they symbol at the beginning means to add all of the different possibilities mentioned in the problem.  is read as “sum of”.