Chapter 4 Structure of the Atom. Section 4.1. Democritus (460-370 BC) Matter is composed of empty space through which atoms move Atoms are solid, homogeneous, indestructible and indivisible Different kinds of atoms have different sizes and shapes
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Chapter 4 Structure of the Atom
The nucleus is the tiny positive core of the atom which contains most of the mass of the atom.
The proton (p+) is the positively (1+) charged particle found in the nucleus of the atom. It has a relative mass of one.
The neutron (no) is the particle with no charge (0) found in the nucleus of the atom. It has a relative mass of one.
The electron (e-) is the negatively (1-) charged particle found in the electron cloud outside of the nucleus. It has very little relative mass by comparison.
ACTUAL MASS (g)
Obj. 5…Subatomic Particles
PROPERTIES OF SUBATOMIC PARTICLES
9.11 x 10-28
1.67 x 10-24
1.67 x 10-24
(change atomic # = change of element).
** (+) charge = less e- than p+
** (-) charge = more e- than p+
(a.k.a. mass #)
Potassium-39 Potassium-40 Potassium-41
Example: The atomic mass of Chlorine (Cl) is 35.453 amu. Chlorine exists naturally as 75% chlorine-35 and 25% chlorine–37.
.75770 x 34.969 amu = 26.496 amu
.24230 x 36.966 amu = 8.957 amu
Weighted average atomic mass of Cl =
(26.496 + 8.957) = 35.453 amu
avg. of allisotopes that exist in nature.
- abundance of isotope is just as important as mass!
Natural copper (Cu) consists of 2 isotopes ...
Copper - 63 (mass = 62 .930 g/mole)
Copper - 65 (mass = 64 .930 g/mole)
mass x abundance for each isotope
Step 1 :
add the two values from step 1 together
Step 2 :
62 .93 x .69 =
64 .93 x .31 =
ATOMIC # CHANGE