Chemistry - Unit 3 test
What is the number of protons in phosphorus-31? (use element chart)
15
How many electrons are in an atom that has an atomic number of 34, an atomic mass of 74 and a charge of -2?
36
Which of the following is/are conclusions based on Rutherford's gold foil experiment? 1: Atom is mostly empty space 2: The nucleus is positively charged 3: The atom has a small dense nucleus 4: All answers are correct
4
How many neutrons in C-14?
8
Which scientist saw the atom as a solid sphere?
Dalton
Who was the Greek philosopher who called the smallest particle of matter as "atom"?
Democritus
Which of these particles was discovered first?
electrons
Two isotopes of carbon are carbon-12 and carbon-14. These isotopes differ from one another by two protons. (T or F)
false. would not be protons
Negative ions form when atoms _________ valence electrons.
gain
If the number of electrons in an atom changes you make a(n) __________________.
ion
Isotopes are atoms of the same element with different #'s of __________ & therefore different __________.
n^0 ; atomic masses
What is an anion's charge?
negative
What is the charge of an anion?
negative
What did James Chadwick discover?
neutron
Particles in an atom that are neutral and have no charge are
neutrons
What quantities vary between isotopes of an element?
neutrons and atomic mass
the central region of an atom where its neutrons and protons are is its
nucleus
What is a cation's charge?
positive
The positive particles of an atom are
protons
An atom is electrically neutral when
protons and electrons are the same
While making his model of an atom, what structure did Rutherford discover (containing protons and neutrons)?
the nucleus
The atomic mass of an element is the ___.
weighted average of the masses of the isotopes of the element
Which model involved gold foil?
Rutherford model
Where are electrons of an atom found?
electron cloud
If an element gains 2 electrons, what charge will it have when it becomes an ion?
-2
an atom with atomic number 6 would have how many protons
6
Which model is this?
Bohrs
Chlorine has two naturally occurring isotopes, Cl-35 and Cl-37, The atomic mass of chlorine is 35.45. Which of these two isotopes of chlorine is more abundant?
Cl-35
In the Thomson Model, he discovered the existence of what particle?
Electrons
According to the Bohr Model, electrons are only found in specific orbits around the nucleus called __________________________
Energy Levels
If X is the symbol for an element, which of the following two symbols represent isotopes of the same element? I. 77^35X II. 77^33X III. 81^37X IV. 81^35 X
I and IV
Which model of the atom proposed that atoms were positive spheres with negative electrons in them?
Plum Pudding Model
The atomic number of an elements is the total number of which particles in the nucleus?
Protons
Which statement best describes an electron?
Smaller mass than a proton and a negative charge
Which model is this?
Thomson model
What do these isotopes of carbon all have in common?
atomic number and electrons
In Dalton's Atomic Theory, all elements consist of __________ that cannot be divided.
atoms
Ions are:
atoms with a positive or negative charge
Which scientist developed the plum pudding/chocolate chip cookie model
thomson
