MATTER UNIT STRUCTURE OF AN ATOM. Atom : the smallest unit of matter that retains the identity of...
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Transcript of MATTER UNIT STRUCTURE OF AN ATOM. Atom : the smallest unit of matter that retains the identity of...
•THE NUCLEUS IS THE SMALLEST PART
OF THE ATOM, BUT CONTAINS ALMOST ALL OF THE MASS OF AN ATOM.
•THE MAJORITY OF THE ATOM IS EMPTY SPACE.
ATOM
ATOMIC STRUCTURE Atoms are composed of 2 regions:
Nucleus: the center of the atom that contains the mass of the atom
Electron cloud: region that surrounds the nucleus that contains most of the space in the atom Nucleus
Electron
Cloud
ATOMIC STRUCTUREThe nucleus contains 2 of the 3 subatomic particles:
Protons: positively charged subatomic particlesNeutrons: neutrally charged subatomic particles
The 3rd subatomic particle resides outside of the nucleus in the electron cloud
Electron: the subatomic particle with a negative charge and relatively no mass
Atomic ParticlesParticle Charg
eMass
#Location symbol
Electron
-1 0 Electron cloud
e-
Proton +1 1 Nucleus p+
Neutron
0 1 Nucleus n0
HOW DO THESE PARTICLES INTERACT?
Protons and neutrons are in the tiny positively charged nucleus accounting for most of the mass of the atom
The negatively charged electrons are small and have a relatively small mass but occupy the larger volume of space outside the nucleus
HOW DO THE SUBATOMIC PARTICLES BALANCE EACH OTHER?
In an atom: The # of protons = The # of electrons
If 20 protons are present in an atom then 20 electrons are there to balance the overall charge of the atom—atoms are neutral
The neutrons have no charge they do not have to equal the number of protons or electrons
THE NUMBER OF PROTONS
IDENTIFIES THE ATOM.
• AN ATOM WITH 6 PROTONS = CARBON
• AN ATOM WITH 8 PROTONS = OXYGEN
• AN ATOM WITH 20 PROTONS = CALCIUM
ATOMIC STRUCTURE
the number of protons in an atom
the number of protons and neutrons in an atom
He2
4 Atomic mass
Atomic number
# of electrons = # of protons
# of neutrons = Atomic mass – # of protons
HOW EXACTLY ARE THE PARTICLES ARRANGED?
Bohr Model of the atom:All of the protons and the neutrons
The 1st ring can hold up to 2 e-
The 2nd ring can hold up to 8 e-
The 3rd ring can hold up to 8 e-
The 4th ring and any after can hold up to 18 e-
ATOMIC STRUCTURE
Electrons are arranged in Energy Levels
or Shells around the nucleus of an
atom.• First Shell a maximum of 2 electrons
• Second Shell a maximum of 8
electrons
• Third Shell a maximum of 8
electrons
• Fourth Shell a maximum of 18
electrons
DETERMINING THE NUMBER OF PROTONS AND NEUTRONS
Li has a mass number of 7 and an atomic number of 3 Protons = 3 (same as atomic #) Neutrons= 7-3 = 4 (mass # - atomic
#) Ne has a mass number of 20 and
an atomic number of 10 Protons = 10 Neutrons = 20 - 10= 10
WHAT ABOUT THE ELECTRONS?
The electrons are equal to the number of protons So e- = p = atomic #
Ex: He has a mass # of 4 and an atomic # of 2 p+ = 2 no = 2 e- = 2
DETERMINE THE NUMBER OF SUBATOMIC PARTICLES IN THE FOLLOWING: Cl has a mass # of 35 and an
atomic # of 17 p+ = 17, no = 18, e- = 17
K has a mass # of 39 and an atomic # of 19 P+ = 19, no = 20 e- = 19
WHAT DOES CARBON LOOK LIKE?
Mass # = 12 atomic # = 6
p+ = 6 no = 6 e- = 6
6 p and 6 n live in the nucleus