Chapter 3 Flashcards
Sulfur mustard or mustard gas is a chemical weapon that causes blisters on the skin and in the lungs. Its chemical formula is C4H8Cl2S. What is the molar mass of this compound?
M = (4 x 12.01g/mol) + (8 x 1.008g/mol) + (2 x 35.45g/mol) + (1 x 32.07g/mol) = 159.074g/mol
The smallest particle of an element that retains the chemical properties of that element.
Atom
A model of the atom that assumed the electrons were negatively charged particles spread throughout a diffuse, positively charged matrix.
The Plum Pudding Model
The short range proton-neutron, proton-proton, and neutron-neutron forces that hold the nuclear particles together
Nuclear Forces (or the Strong Force)
Strontium nitrate is used as a red colorant in fireworks. The formula for the compound is Sr(NO3)2. What is the formula mass of this compound?
M = (1 x 87.62u) + (2 x 14.01u) + (6 x 16.00u) = 211.64u
How many formula units are there in 0.084mol of potassium sulfide, K2S?
How did Rutherford explain the mass and volume of the nucleus?
The nucleus occupies only a tiny volume of the entire atom, yet contains over 99.9% of the atom’s mass. Therefore it is a very dense, positively charged area.
The tiny central core of an atom having a dense, positive charge
Nucleus
A symbol that indicates the identity of a particular atom using its symbol, along with the number of protons as a subscript and the mass number as a superscript, preceding the symbol.
Nuclide symbol
A mass defined as being exactly 1/12th the mass of a carbon-12 atom.
Atomic mass unit (u or amu)
The identity of an atom is determined by the number of these in the atom.
Protons
The total number of protons and neutrons in a nucleus
The mass number (A)
What is the mass of 0.085mol of iodoform (CHI3), a chemical used as a disinfectant, whose smell is sometimes described as the smell of a hospital?
A neutral subatomic particle, found in the nucleus of an atom.
Neutron
The general term for a specific isotope of an element
Nuclide
Calculate the number of moles of lithium sulfate in a 16.5g sample of the compound.
A law that states that “a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound.”
The Law of Definite Proportions
How many moles are there in a 2.61g sample of aluminum carbonate, Al2(CO3)3?
The relative charges of the electron, neutron, and proton, in that order.
-1, 0, +1
J.J. Thomson’s cathode ray tube experiment led to the discovery of which subatomic particle?
The electron
If a sample of thiourea (CH4N2S) contains 2.91 x 1018 molecules, how many moles is this equal to?
What is the mass of 6.90mol of Iridium?
In the hyphen notation carbon-12, the 12 represents this.
The mass number
The center of an atom, composed of protons and neutrons.
Nucleus
The atom that was chosen as the standard for the relative atomc mass scale.
Carbon-12
What parts of Dalton’s atomic theory are now known to be incorrect?
- Atoms are not indivisible (they are composed of smaller particles).
- All atoms of a given element are not necessarily identical (many elements have isotopes).
How many hydrogen atoms are there in 4.50mol of diammonium phosphate, (NH4)2HPO4?
A law that states “mass is neither created nor destroyed during ordinary chemical reactions or physical changes.”
The Law of Conservation of Mass
If a sample of silver contains 5.97 x 1024 atoms, how many moles are there?
Selenium has five different stable isotopes. Using the data below, calculate that average atomic mass of selenium to two decimal places.
Nuclide Isotopic Mass %Abundance
Se-74 73.922amu 0.89%
Se-76 75.919amu 9.37%
Se-77 76.920amu 7.63%
Se-78 77.917amu 23.77%
Se-80 79.917amu 49.61%
Se-82 81.912amu 8.73%
Note: You may have to stop in the middle of the calculation, press equals, and then continue.
(73.922u x 0.0089) + (75.919u x 0.0937) + (76.920u x 0.0763) + (77.917u x 0.2377) + (79.917u x 0.4961) + (81.912u x 0.0873) = 78.96u
The number of protons in the nucleus of an atom is given by this number.
The atomic number (Z).
This negatively charged, smallest subatomic particle is about 1,836 times lighter than the other two subatomic particles.
Electron
How many molecules of carbon monoxide would there be in 3.8mmol?
Complete the table:
What did Robert A. Millikan’s oil drop experiment allow scientists to determine?
The mass of the electron
How many oxygen atoms in NaNO3? How many in Ca(NO3)2 ? How many in Al(NO3)3? What is the general rule for counting atoms in parentheses?
3, 6, 9; multiply the subscript outside the parentheses by the subscripts inside the parentheses.
Ernest Rutherford’s gold foil experiment gave experimental evidence suggesting that atoms have these.
Nuclei
A law that states “if two or more different compounds are composed of the same two elements, then the ratio of the masses of of the second element combined with a certain mass of the first element is always a ratio of small whole numbers.”
The Law of Multiple Proportions
A positively charged subatomic particle, found in the nucleus of an atom.
Proton
Atoms of the same element having a different number of neutrons.
Isotopes
The weighted mass of all the naturally occurring isotopes of an element.
Average atomic mass
