Download PreAP Chapter 3 Notes

PreAP Chapter 3 Notes
____________________ was the early Greek philosopher who is credited with the concept of the atom (atomos) – which means
____________________
________________________________________ states that the elements in a specific compound always contain the same proportions by
mass
________________________________________ states that if two or more different compounds are composed of the same two elements,
then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers
____________________ is an English school teacher who proposed the law of conservation of mass, the law of definite proportions, and the
law of multiple proportions. He is also known as the ____________________________________________________________
Dalton’s atomic theory
1.
All matter is composed of very small particles called ____________________
2.
Atoms of a given element are identical in ____________________, ____________________, and other properties; atoms of
different elements differ in these properties.
3.
Atoms cannot be ____________________, ____________________, or ____________________
4.
Atoms of ____________________ elements combine in simple ____________________ ratios to form chemical compounds.
5.
In chemical reactions, atoms are ____________________, ____________________, or ____________________
Two aspects of Dalton’s atomic theory proven to be incorrect:
a.
We now know atoms are ____________________
b.
Atoms of the same element can have different ____________________
____________________ - smallest particle of an element that retains the ____________________ of that element.
Two regions of an atom
1.
____________________ --small region near the center of the atom. Composed of two particles—the ____________________
which is ____________________ charged and the ____________________ which is ____________________ charged.
2.
____________________ --composed of ____________________ charged electrons. It is very large in comparison to the
nucleus.
____________________ particles—protons, neutrons, electrons.
____________________ tubes—the instrument used in the discovery of the electron.
____________________ is the man credited with the discovery of the electrons in the late _____
____________________ discovered the mass of the electrons.
Knowledge of electrons led to two inferences about atomic structure:
1.
Because atoms are electrically ____________________, they must contain ____________________ charge to balance the negative
electrons.
2.
Because electrons have so little mass, atoms must contain other particles to account for most of their ____________________
Nucleus of the atom—discovered by ________________________________________
Gold foil experiment—actually done by ____________________ and ____________________
Observations:
a.
Majority of the ____________________ particles penetrated foil ____________________
b.
About ____________________ in ____________________ were ____________________ deflected
c.
About ____________________ in ____________________ were deflected ____________________
Conclusions:
1.
___________________ of the atom and the ____________________ charge are concentrated in small regions called
____________________
2. Most of the atom is ______________________________.
3.
__________________________of charge on the nucleus is__________________ for different atoms.
4.
Number of ____________________ outside the nucleus + number of units
of ____________________ (to account for the fact
that the atom is electrically ____________________
Atoms are electrically neutral because they contain equal numbers of ____________________ and ____________________
Rutherford’s Gold Foil Experiment Summary
1.
What kinds of particles are being emitted by the radioactive source and what is their charge?
_________________________________________________________________________________________________________________
2.
Toward what are the alpha particles being directed?
_________________________________________________________________________________________________________________
3.
What happens when the charged particles strike the surface of the gold foil?
_________________________________________________________________________________________________________________
4.
What was the purpose of the fluorescent screen?
_________________________________________________________________________________________________________________
5.
What did Rutherford conclude from this gold foil experiment regarding the amount of empty space in the atom? Why was he able
to conclude this?
_________________________________________________________________________________________________________________
_________________________________________________________________________________________________________________
6.
How does the deflection path of a charged particle that strikes the center of a gold atom differ from the path of a particle that passes
only near the center?
_________________________________________________________________________________________________________________
7.
Based on this experiment, where is most of the positive charge and mass of an atom found?
_________________________________________________________________________________________________________________
8.
What would have been observed in the positive charge of an atom had been thinly spread out throughout the atom?
_________________________________________________________________________________________________________________
________________________________________the short-range proton-neutron, proton-proton, and neutron-neutron forces that hold the
nuclear particles together
Mass of one____________________= mass of one ____________________= mass of 1837 ____________________
Atomic number

number of ____________________in the ____________________of the atom.

number of ____________________ ____________________ the element and is equal to the number of ____________________

symbol is Z.
____________________are atoms of the same element that have different masses because they have different numbers of
____________________, but they still have similar chemical ____________________
Mass number

approximate ____________________of an atom (____________________)

the number of ____________________+ the number of ____________________
____________________is the general term for any isotope of any element
______________ _____________
___________ (1 _______) is exactly 1/12 the mass of a carbon-12 atom.
______________ _____________ _____________ is the weight average of the atomic masses of the naturally occurring isotopes of an
element.
Ave. Atomic mass = (%abundance × mass of isotope 1) + (%abundance × mass of isotope 2) +…..
Moles
____________________ (_________) is the amount of a substances that contains as many particles as there are atoms in exactly 12 g of
carbon-12.
____________________number - ____________________ - is the number of particles in exactly ____________________mole of a pure
substance. Just as one dozen = 12 somethings, one mole = ____________________somethings.
The mass of one mole of a pure substance (element or compound) is called the ________________________________________of that
substance. The unit is _____________.
Examples:
How many grams are in 2.0 moles of Carbon?
_________________________________________________________________________________________ = ________________
How many moles are in 0.58 g Al?
_________________________________________________________________________________________ = ________________
How many moles are equal to 1.20 x 1025 atoms of sodium? (Na)
_________________________________________________________________________________________ = ________________
How many atoms are in 0.750 mol of zinc? (Zn)
_________________________________________________________________________________________ = ________________
What is the mass in grams of 4.75 x 1024 atoms of silver? (Ag)
_________________________________________________________________________________________ = ________________
What mass of Antimony (Sb) contains the same number of atoms as 9.0 g of aluminum?
_________________________________________________________________________________________ = ________________