Download Protons, Valence Electrons, and the Periodic Table

Protons, Valence Electrons,
and the Periodic Table
PROTONS
Protons are the most important particle
that determines the identity
of the element.
• The # of protons for a specific element
is always the same and equals its atomic
number on the periodic table
Atomic # = # of Protons
• Elements are arranged by increasing
atomic number on the periodic table.
•
•
•
•
•
H–1
He – 2
Li – 3
Be – 4
and so on….
Valence Electrons
• Are the electrons on the outermost
energy level of the atom.
• The # of valence electrons determine
the atoms chemical properties,
including reactivity.
Groups – 18 columns on the
periodic table
Elements are
in groups
based on the
number of
valence
electrons they
have!
Periods – 7 rows on the
periodic table
Elements are in
periods based
on the number
of energy
levels
(orbitals) they
have in their
electron cloud.
Nucleus
•
•
•
•
Center of the atom
Made up of Protons and Neutrons
Makes up the atoms MASS
Positively Charged!
Charge of the Nucleus
• Equal to the total #
of Positive
PROTONS in the
Nucleus!
• Neutrons don’t count
– they have NO
charge
• What is the charge
of the nucleus for
this lithium atom?
• +3
Electron Cloud
• Area around the
nucleus where
electrons are found.
• Negatively Charged
Atoms are Neutral!
• The number of positive protons is equal
to the number of negative electrons so
the overall charge of an atom is zero
(neutral)
• # of Protons = # of Electrons
+3 protons
-3 electrons
0 charge
The 4 Neutrons don’t count
They have NO charge
What is the charge of the
nucleus in the atom below
• +4
• The nucleus has 4
positive protons.
• The 5 neutrons don’t
count because they
have NO charge.
What element does this
atom model represent?
• Neon
• It has 10 electrons
so it has 10 protons
• The # of electrons =
the # of protons
• The # of protons =
the atomic # which
is # 10 on the
periodic table
What element is this?
• Nickel
– It has 28 protons
– So the atomic # is 28!
• What is the Mass of
this atom?
– 59 amu
28 protons + 31 neutrons = 59
– The mass = the total # of
protons and neutrons in the
nucleus of atoms.
Atom Models
What element is this?
• Neon
• It has 10 protons
• So it is atomic # 10
on the periodic table
Energy Levels (Orbitals)
• Levels within the electron cloud that
hold a specific # of electrons.
– 1st level - 2 electrons
– 2nd level - up to 8 electrons
– 3rd level – up to 8 electrons
– Sometimes up to 18 for transition metals
Valence Electrons
The electrons in the outermost energy level of the atom.
• What element is this?
– Seaborgium: 106 protons
– Atomic # 106
• How many Electrons?
– 106; equal to the # of protons
• How many valence
electrons does it have?
– Only 2 on the outer level
ELEMENTS
• Elements are the atoms that make up our
universe!
Elements
• Atoms are the simplest form of an
element that cannot be broken down
chemically.
• They maintain the element’s properties.
• Each element is an atom that has the
same number of protons
– – i.e. the same atomic number on the
periodic table of elements.
Element - hydrogen
• H – Hydrogen
Element - Helium
• He – Helium
The Elements are found on the
Periodic Table of Elements