Chemistry #1: The Atom and the Periodic Table: Isotopes

Isotopes

different forms of the same element due to different numbers of neutrons

Where is the average atomic mass of an element on the periodic table?

on the periodic table is the weighted average of all isotopes based on relative abundance (the decimal under the atomic number)

"A" symbolizes...

the exact mass number

"Z" symbolizes...

the atomic number for all versions of the element

How is average atomic mass decided?

it is skewed to the isotope the is more common in nature (ex. Carbon -12, 12.011)

What are the vertical rows on the periodic table called?

groups/columns

What are the horizontal rows on the periodic table called?

rows/periods

ion

a charged particle

cation

a positive metal ion

How does a cation form?

it loses it's outer shell and becomes positive by how many outer shell electrons it has

Hint to find the charge of a metal:

it's last number on the electron configuration is it's column number if its in an A column

anions

a negative nonmetal ion

How do anions form?

metals give up their outer shell electrons to become positive ions and nonmetals fill up their outer shell to 8 total electrons to become negative ions ( The Octet Rule )

Hint to finding the charge of a nonmetal anion:

count over from far right column negative

Example of Anion: Chlorine

chlorine as an ion finds one more electron, so its configuration is 2,8,8

17 positive and 18 negative

net of -1

Cl-1