Atomic Theory
What was the conclusion of the Gold Foil Experiment?
-the atom is mainly empty space
-the nucleus is dense and central
What are the laws of conservation?
-charge, mass, and matter must be conserved in all chemical reactions
What is the purpose of the periodic table?
To organize elements based on their properties and atomic structure.
Define a mole in chemistry
A mole is 6.022 × 10²³ particles of a substance.
What are the three states of matter?
Solid, liquid, gas.
What is an ionic bond?
A bond formed by the transfer of electrons from one atom to another.
A bond formed between a metal and nonmetal
A bond between two ionized substances
What part of the atom is positively charged?
-nucleus (protons)
What is the general type of reaction that follows the general formula:
A + B --> AB
Synthesis
How can you determine the molar mass of a compound using the reference tables?
By summing the atomic masses of all elements in the compound
How do you convert grams to moles?
Divide the mass of the substance by its molar mass.
At constant temperature, the pressure of a gas is inversely proportional to its volume.
Describe a covalent bond
A bond formed by the sharing of electrons between two atoms.
A bond formed between two nonmetals
Which atomic model includes orbits that show electrons at distinct energy levels?
-Bohr model
-Planetary Model
What is a catalyst?
A substance that increases the rate of reaction by changing the pathway and lowering the activation energy
What information can be found in the solubility table?
It shows which compounds are soluble or insoluble in water.
Calculate the number of moles in 50 grams of NaCl.
50 g NaCl × (1 mol NaCl/58.44 g NaCl) ≈ 0.856 moles
What is the difference between an element and a compound?
An element consists of one type of atom; a compound consists of two or more different atoms chemically bonded.
What is electronegativity and how does it affect bonding?
Electronegativity is the tendency of an atom to attract electrons; it influences bond polarity
How is the average atomic mass calculated?
using a weighted average of all the naturally occurring isotopes of an element
What are the coefficients for the following reaction when balanced?
__Al + __O2 --> __Al2O3
4 Al + 3 O2 --> 2 Al2O3
What does the term "half-life" refer to?
The time required for half of a radioactive substance to decay.
What does IUPAC stand for?
International Union of Pure and Applied Chemistry
Describe what happens to the particles of a substance as it changes from solid to liquid.
The particles gain energy and move apart as the substance melts.
Potential energy increases while kinetic energy stays the same
What rule helps determine how many bonds an element can form and what does it mean?
octet rule: an element wants 8 valence electrons to become stable
Define isotope and provide an example
-isotopes are atoms of the same element with different mass numbers
-isotopes are atoms with the same number of protons but different number of neutrons
In terms of energy, explain the difference between endothermic and exothermic reactions
endothermic reactions have a net gain in energy; they take energy in; they absorb energy
Exothermic reactions have a net loss of energy; they lose energy; they release energy
Explain how to use the reference tables to find the phase of an element
Using Table S you have to look at the boiling/condensing point and the melting/freezing point and determine where the element is a solid/liquid/gas
If 2 moles of A react with 3 moles of B, how many moles of C can be produced if the reaction is A + 1.5B → C?
2 moles of A can produce 2 moles of C; 3 moles of B can produce 2 moles of C, so 2 moles of C is the answer.
Define vapor pressure and its significance in physical chemistry.
Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid or solid phase; it indicates a substance's volatility.
describe how you would find the oxidation state of an element within a compound
first, determine the oxidation states of any element that only has one available according to the PTE,
second, set up the algebraic equation based on the molar quantities of all the atoms present
third, solve for the missing oxidation state