Name ___________________________________
Atomic Structure
Directions: Use pages 280-293 and any notes/info/handouts from class to fill in the blanks.
I. What is an atom?
Atom:_________________________________________________________
______________________________________________________________
First proposed by _____________________.
II. Atomic Structure
Atoms are composed of 2 regions:
_____________: the center of the atom that contains the mass of the atom
______________ ______________ : the region that surrounds the nucleus that contains
most of the space in the atom
____________
____________
III. What’s in the nucleus?
The nucleus contains 2 of the 3 subatomic particles.
____________: positively charged subatomic particles
____________: neutrally charged subatomic particles
IV. What’s in the electron cloud?
The ________ subatomic particle resides outside of the nucleus in the __________
__________.
Electron: the particle with a __________ charge and relatively no __________.
V. How do these particles interact?
Protons and neutrons live compacted in the tiny _______ charged nucleus accounting for all of
the ________ of the atom.
The negatively charged _____________ are small and have relatively no mass but occupy a
large _____________ of space outside of the nucleus.
VI. How do the subatomic particles balance each other?
In an atom: ________________ = __________________
If 2 protons are present in an atom then _______ electrons are there to balance the overall
charge of the atom—atoms are _______________.
The neutron has _____ charge therefore they do not have to equal the number of protons or
electrons.
VII. How do we know the number of subatomic particles in an atom?
Atomic number: indicates the number of ___________ in an atom.
Ex: hydrogen’s atomic number is 1, so hydrogen has _______ proton**.
Ex: carbon’s atomic number is ______, so carbon has _____ protons**.
**The number of ___________ identifies the atom
2 p = ________
29 p = _______
VIII. How do we know the number of subatomic particles in an atom?
Atomic ______ : the number (or sum) of protons and neutrons in the nucleus.
Ex: helium has a mass of ________.
Since it has 2 protons, it must have 2 neutrons.
**number of neutrons = Atomic ________ - # of ________
IX. Determining the number of protons and neutrons:
Li has an atomic mass of 7 and an atomic # of 3
Protons = 3 (same as the # of __________ )
Neutrons = 7 – 3 = 4 (Atomic _________ - # of________ )
Ne has a mass number of 20 and an atomic number of 10.
Protons = _______
Neutrons = ______
X. What about the electrons?
The electrons are equal to the number of ___________.
So protons = __________ = __________ number
Ex: He has a mass number of 4 and an atomic number of 2
p=2
n=2
e-= 2
XI. Determine the number of subatomic particles in the following:
Cl has a mass number of 35 and an atomic number of 17
P = ______ n = _______
e- = ______
K has a mass number of 39 and an atomic number of 20.
P = ______ n = _______
e- = ______