The Periodic Table I Flashcards
The number of protons in the nucleus; The number of protons in the nucleus determines the identity
of an element
Atomic Number (Z)
The sum of the number of protons and the number of neutrons in a nucleus; The total number of nucleons in an atom; The “mass” in mass number does not really talk about the atom’s mass, it’s the number of nucleons; But since the masses of protons and neutrons take up most of the mass
of an atom (electron has negligible mass), the mass number is an approximation of the atomic mass
Mass Number (A)
Particles inside the nucleus
Nucleons
Atoms of the same element do not always have the same number of neutrons, thus differing in mass numbers
Isotopes
Same element = Different mass number
Isotopes
The location of the Mass Number
Northwest
The location of the Atomic Number
Southwest
An atom having an excess proton or electron; Electrically-charged
particles
Ions
Ion with more electrons than protons; Negatively-charged
Anion
Ion with less electrons than protons; Paw-sitively charged
Cation
Each proton and neutron
has a certain mass, and this is calculated by adding up the masses of all the protons and neutrons in an atom
Atomic Mass
Since it is inconveniently
large to measure atoms
using grams/kilograms,
we usually use:
Atomic Mass Units (U)
Used as a standard reference for Atomic Mass
Carbon-12
How many protons, neutrons, and electrons does Carbon-12 have?
6 protons, 6
neutrons, and 6 electrons
1 u (atomic mass units) is approximately:
1.6605 x 10^-24
