Download CHAPTER 3: The Building Blocks of Matter

Name_____________________________________________Date______________Period________
UNIT 1: Atomic Theory
Part I – Atomic Structure
I. Early Atomic Theory□Democritus (400 B.C.)- suggested that the world was made of two
things:
-empty space and
-tiny, indivisible particles called ‘____________’.
□Dalton (early 1800s)- using the experimental observations of others, including Lavoisier and
Proust, he proposed□Dalton’s Atomic Theory1. All elements are composed of _________ particles called atoms.
*2. Atoms of the same element are ____________. The atoms of any one element
are different from those of another element.
* ____________ of an element are not identical.
*3. Atoms cannot be _____________, created, or destroyed.
* Atoms are divisible by a ___________ change.
4. Atoms of different elements can combine with one another in simple, whole
number ratios to form ______________.
5. Chemical reactions occur when atoms are _____________,_____________, or
__________. HOWEVER, atoms of one element are ______ changed into
atoms of another by a chemical reaction.
II. Early Research on Atomic Particles□______________ (1897)- used a cathode ray tube to prove the existence of _____________
charged subatomic particles called _____________. See Figure 3-4, page 70.
□_________________ (1909)- his‘Oil Drop Experiment’ used a device to prove that the charge
of an electron is (____).
□_________________ (1913)- his ‘Gold Foil Experiment’ used a device to prove that the atom
is made up mostly of _________ __________with a small, dense, ______________
charged nucleus. See Figure 3-6, page 72.
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Name_____________________________________________Date______________Period________
□________________ - used a modified cathode ray tube to prove the existence of a positively
charged subatomic particle called a __________. It has equal but _________ charge to
the electron (_____) and a mass _________ times heavier than an electron.
□________________ (1932)- used a device to prove that the nucleus contained ___________
particles of the same mass as the proton called ____________.
III. Isotopes and Atomic Number□_____________Number- is the number of ___________ in an atom. This number is unique
for that element and the atomic number thus identifies the element. Since atoms are
electrically neutral, THE NUMBER OF PROTONS _________ THE NUMBER OF _________.
Example- The atomic number of oxygen is 8. All oxygen atoms have 8 protons in the
nucleus.
□______________- are atoms of the same element that differ in the number of __________ in
the nucleus. _______________ of the same element have the same chemical properties.
THE NUMBER OF NEUTRONS DETERMINES THE PARTICULAR ______________ OF THE
ELEMENT.
□_________ Number- is the total number of ___________ and ___________ in an atom.

Mass Number = protons + neutrons

Neutrons = Mass Number – protons
Practice Problem:
1. How many protons, neutrons and electrons in Oxygen-16
2. How many protons, neutrons, and electrons in Oxygen-17
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