Download Chapter 4 Notes

Name: _______________________________________________ Date: _______________ Period: ________
Chapter 4 Notes
Development of Atomic Theory
1. Democritus named atoms from the Greek word that means ____________________.
2. During Aristotle’s it was believed that all substances were built from the four elements
________________, air, _____________________ and water.
3. By the 1800s Dalton’s ideas replaced the Greeks, and he proposed that all
________________ is made up of individual _______________ that could not be
____________________.
4. There were four major points to Dalton’s theory
a. All elements are composed of ___________________.
b. All atoms of the same element have the same _________________, and atoms of
different elements have different ____________________.
c. Compounds contain atoms of more than one ________________.
d. In a particular compound, atoms of different elements __________________________
combine in the same way.
5. Although Dalton’s theory was widely accepted, scientists began experimenting to see if
Dalton’s theory was true. Thomson’s experiment provided the ________________ evidence
that atoms are made of ______________________ particles.
6. Thomson believed that____________ are neutral, having neither a negative or positive
charge and that the charges were ______________________ ____________________ throughout the
atom. His model was called the ______________ ___________________ model.
7. Rutherford tested Thomson’s model to see if the charges were scattered. He was
surprised when some particles were ________________________.
8. In the Gold Foil experiment, Rutherford shot _________________ particles at a thin sheet of
gold foil. He found that as the alpha particles got closer to the center they were more
_______________________.
9. Rutherford concluded that the positive charges in the atom are ____________________ at the
center called the ___________________________.
Subatomic Particles
10. Rutherford found the first two subatomic particles, and proposed a third particle.
These particles are _________________________, ________________________ and _____________________.
11. Rutherford concluded that the amount of ____________________ charge varies by element.
Each positive charge comes from a _____________________ which is found in the
______________________ of an atom. Each one has a ___________ charge.
12. ______________________, on the other hand, are ____________________ charged and are located
__________________ the nucleus. Each one has a _____________ charge.
13. The ______________________ is a neutral subatomic particle located ________ the nucleus. It
mass is almost _________________ to the mass of a proton.
14. Electrons have a much ___________________ mass than protons.
15. The charge of electrons and protons are the ______________magnitude but the particles
have ____________________ sign.
16. Protons and neutrons are found ___________________ the nucleus and electrons are
_______________________.
Name: _______________________________________________ Date: _______________ Period: ________
17. The number of protons in an atom is the ___________________ number. All atoms of the
same element have the _____________________ number of protons. Atoms of
________________________ elements have ______________________ numbers of protons.
18. The ___________________ ________________________ of an atom is the sum of the
_______________________ and ______________________ in the nucleus of the atom.
19. If you know the atomic number and the mass number of an atom, you can find the
number of neutrons by subtracting.
Number of neutrons = ______________________ number-_________________ number
20. __________________________ are atoms of elements that have the same numbers of
_____________________, but different numbers of _______________________. Isotopes of elements
have different _________________________ numbers.
Bohr Model
21. Bohr’s model of the atom differed from Rutherford’s in that it focused on the
_________________________.
22. In Bohr's model, electrons move with constant speed in __________________orbits around
the nucleus. Each electron has a _________________ amount of energy.
23. The possible energies that electrons in an atom can have are called _____________________
_____________________.
24. An electron in an atom can move from one energy level to another when the atom
____________________ or __________________ energy.
Modern Atomic Theory
25. An _____________________ cloud is a visual model of the most likely locations for
_______________________ in an atom. The cloud is denser at those locations where the
_____________________________ of finding an electron is high.
26. The electron cloud represents all the ________________________ in an atom. An orbital is a
region of _____________________ around the nucleus where an electron is
________________________ to be found.
27. Each energy level can contain a certain number of orbitals. Each orbital can contain
____________ electrons at most as seen in the table below:
Energy
Level
Number of
Orbitals
Maximum Number of
Electrons
1
2
3
4
28. An ________________________ configuration is the arrangement of electrons in the
__________________ of an atom.
Name: _______________________________________________ Date: _______________ Period: ________
29. The most stable electron configuration is the one in which the electrons are in orbitals
with the _________________________ possible energies. When all the electrons in an atom
have the possible energies, the atom is said to be in its __________________________ state.
30. If an atom _____________________ enough energy, one of its electrons can move to an orbital
with a ______________________ energy.