3-1 Inside Atoms
Pages 76-80
nucleus p 76
•central core of an
atom containing
protons and usually
neutrons
nucleus
proton p.76
•small positively
charged particle in
the nucleus of an
atom
proton
neutron p 76
•small uncharged
(neutral) particle
in the nucleus of an
atom
neutron
electron p 76
• a tiny, negatively
charged, high-energy
particle that moves in
the space outside the
nucleus of an atom
electron
electron
electron
• Let’s review your
answers!
Yes
Yes
Yes
No
No
No
Yes
No
No
No
Yes
No
No
Yes
Yes
atomic number p 77
•the number of
protons in the
nucleus of an
atom
atomic number
mass number p 266
mass number = protons + neutrons
also called atomic weight
What is the mass number?
What is the mass number?
atomic mass unit (amu) p 77
•a unit of
measurement for the
mass of particles in
atoms
atomic mass unit (amu)
The mass of a proton or a
neutron = 1 atomic mass
unit
1 neutron = 1 amu
1 proton = 1 amu
atomic mass unit (amu)
How many atomic mass units?
How many atomic mass units?
valence electrons p 79
•the electrons that are
farthest away from the
nucleus of an atom and
involved in chemical
reactions (the # of electrons
in the outer-most orbital)
How many valence electrons?
How many valence electrons?
How many valence electrons?
electron dot diagram p. 80
• a representation of the
number of valence electrons
in an atom using dots placed
around the symbol of an
element
electron dot diagrams
Turn to page 80
•Draw the electron
dot diagrams for
Carbon and Neon
in your notes
electron dot diagrams
isotopes
p 266
an atom with the same
number of protons, but a
DIFFERENT number of
NEUTRONS from other
atoms of the same element
Isotope
isotopes
atomic mass/average
atomic massp 82
• atomic mass (average
atomic mass) is the
AVERAGE mass
(p + n) of an
element’s atoms
atomic mass/average atomic
mass
atomic
mass/
atomic
weight
atomic mass/atomic weight
vs. mass number
atomic mass/atomic weight average mass for a large group
of the same kind of atoms
mass number - # of protons +
neutrons for 1 specific atom