Download ps ch 4 rev 2015ans

Ch 4 Review 2015-Answers
1.
The Greek philosopher Democritus coined what word for a tiny piece of matter that cannot be
divided? Atomos-individisible
2.
Which subatomic particle has a negative charge? electron
3.
What is a good analogy for an electron in an atomic orbital? Propeller on a plane or a bee in a jar
4.
What are the 3 types of subatomic particles and label the masses of each? Proton 1 amu, neutron 1
amu, electron 1/1836 amu
5.
What is unique for any given element? Protons or atomic number
6.
The glowing of a neon light is caused by electrons emitting energy as they jump from higher excited state to a lower energy level
7.
Democritus thought that matter was made of tiny particles called atoms that made up everything
8.
In Niels Bohr’s model of the atom, electrons move in orbits around the nucleus based on their
energy
9.
Who provided evidence for the existence of a nucleus in an atom? Rutherford with his gold foil experiment where alpha particles shot throught the foil instead of mostly bouncing back which proved
atoms are empty space mostly
10.
The number of protons in one atom of an element is that element’s atomic number
11.
Describe John Dalton’s atomic theory? All matter is made of atoms, like atoms are same, different
atoms are different, atoms combine to make compounds
12.
According to John Dalton’s observations, when elements combine in a compound, the ratios are always the same or constant
13.
Rutherford’s gold foil experiment provided evidence for the existence of the dense nucleus and that
atoms are mostly empty space
14.
J. J. Thomson’s experiments provided evidence that an atom has charges with and electron with
negative charge with his cathode ray tube experiment.
15.
Rutherford’s gold foil experiment.-What caused some of the alpha particles to bounce straight back
from the gold foil? A very few Nuclei collided and then the fired alpha particle bounced back
16.
If 2 grams of element X combine with 6 grams of element Y to form compound XY, how many
grams of element Y would combine with 10 grams of X to form the same compound?30 grams as the ratio is
3x=y
17. Draw John Dalton’s model of the atom? No subatomic parts just a ball with no parts
18.
How was Bohr’s atomic model similar to Rutherford’s model? Both had nucleus and electrons on
the outside in large space
19.
Describe the Bohr’s atomic model? Protons and neutrons in the nucleus with electrons in orbitals
or energy levels orbiting around.
20.
What is different about oxygen-17 and oxygen-18?different isotopes with 1 neutron difference
21.
What are subatomic particles? Parts of the atom like proton, electron and neutron
22.
Describe the energy relationship between electrons and atomic orbitals?closest orbitals are the
ground state and most stable, farthest out have most energy but unstable
23.
In an atomic model that includes a nucleus, positive charge is in the nucleus as it is protons
24.
Suppose an atom has a mass number of 20. What is true beyond any doubt? The protons and neutrons total 20 together
25.
To find the number of neutrons in an atom, you would subtract mass number from atomic number
26.
John Dalton concluded that all the atoms of a single ____element_____ have the same mass.
2 of 3
27. Explain in detail the Thomson model of the atom and why it was important to the understanding of the atom
as we know it today.
The Thompson model was based on the idea of Plum Pudding or a chocolate chip cookie. The pudding
was the positively charged substance and inside of that scattered around would be the plums or the
negatively charged electrons. The model proved the existence of charged electrons in the atom.
28. What was the significance of Rutherford’s experiment and what did it lead to? Rutherfords gold foil
experiment provided proof that the atom is mostly empty space with a positive dense nucleus. It helped
lead to the idea of a planetary model of the atom.
29. Compare and contrast the beliefs of Democritus and the beliefs Bohr on the atom. Democritus believed that
atoms were small hard particles that could not be divided. He thought that the atoms could make up
everything but there were different types. With the Bohr model, we realized that the atom can be
divided into its parts of proton,neutron, and electron and also that atoms are empty space. Bohr agrees
with Democritus on the fact that atoms make up everything and each element has a different atom.