Chapter 5 Review Answer Key
Atom—smallest unit of matter to still retain its properties
Proton—positively charged subatomic particle found in the nucleus of an atom
Neutron—subatomic particle without a charge that is found in the nucleus of an atom
Electron—negatively charged subatomic particle with extremely small mass found in the empty space outside of an atom
Nucleus—dense center of an atom where most of the mass is located
Isotopes—two atoms that have the same number of protons but different number of neutrons (same atomic number but different mass number)
Atomic number—number of protons found in the nucleus of an atom
Mass number—number of protons and neutrons found in the nucleus of an atom; since the mass of an electron is so small, the number of protons and neutrons together comprise what can be considered as the entire mass of an atom
Atomic mass—the weighted average of all of the isotopes of an element
Democritus—first to theorize the existence of atoms (tiny indivisible particles that make up everything)
Dalton—first to experiment and describe the nature of atoms, found Dalton’s Atomic Theory
Thomson—discovered the electron, which proved existence of subatomic particles
Chadwick—discovered the neutron
Goldstein—discovered the proton
Rutherford—proved that atoms have a dense positively charged center where most of an atom’s mass is located (the nucleus)
Dalton’s theory is that 1) all elements are made up of tiny indivisible particles called atoms, 2) that atoms of the same element are identical, and no two elements are the exact same, 3) that atoms can either mix together physically or combine chemically in simple, whole number ratios, and 4) that when reacting chemically, atoms can separate, join together, or rearrange, but atoms of one type never change into atoms of another.
Thompson put gas into a glass tube at a near-vacuum and put a charge through it, causing a beam of light. When an electromagnet was placed near the tube, the beam was deflected away from the negative and towards the positive. The results were the same for all gases he used, thus he proved that since atoms are electrically neutral, there must be a particle the atom is made of that has a negative charge—he named it the electron.
Rutherford shot small positively charged particles at a thin piece of gold foil and recorded the results on photo paper. He expected the particles to be deflected slightly, but all to pass through, but the actual result was that most particles passed through completely, but some were deflected at various different angles. It proved that most of the volume of an atom had to be empty space, but that there was a small, positively charged center that was dense enough to deflect the particles—which he called the nucleus.
An atom is electrically neutral because it has the same number of protons and neutrons.
The identity of an atom is determined by the number of protons in the nucleus.
The proton and neutron both have relatively large masses (1 amu) when compared to the electron (1/1840th of 1 amu).
Carbon-14 has 2 more neutrons(8) than carbon-12 (6).
The mass number would be 39 (mass # = # protons + # neutrons) = 19 + 20
The mass number would be 16 (8+8=16), which would be Oxygen.
Chlorine-35 has 17 protons, 17 electrons and 18 neutrons; argon-40 has 18 protons, 18 electrons and 22 neutrons; zinc-67 has 30 protons, 30 electrons and 37 neutrons; silicon-28 has 14 protons, 14 electrons and 14 neutrons.
It has 17 electrons. (Because the atomic number is 17)
Sn—50, Po—84, Te—52, Se—34, K—19, Rb—37
The names and symbols are
H—Hydrogen
O—Oxygen
Na—Sodium
Ca—Calcium
Pt—Platinum
Mn—Manganese
Cl—Chlorine
P—Phosphorus
Be—Beryllium
Fe—Iron
C—Carbon
Ne—Neon
Kr—Krypton
Xe—Xenon
Rn—Radon
Rb—Rubidium
Cs—Cesium
Fr—Francium
Sr—Strontium
Ba—Barium
Ag—Silver
Cd—Cadmium
Sn—Tin
Sb—Antimony
Co—Cobalt
He—Helium
U—Uranium
Al—Aluminum
Cr—Chromium
S—Sulfur
F—Fluorine
B—Boron
K—Potassium
Si—Silicon
Li—Lithium
N—Nitrogen
Mg—Magnesium
I—Iodine
Ar—Argon
Bi—Bismuth
Br—Bromine
Pb—Lead
As—Arsenic
Hg—Mercury
Au—Gold
Zn—Zinc
Se—Selenium
Cu—Copper
W—Tungsten
Ni—Nickel