Chemical Formula
What is the difference between the Empirical and Molecular formulas?
Molecular formula has the subscripts that give the exact number of each element in the formula of a compound while an empirical formula has been reduced to the lowest terms.
What is the Atomic Theory of Matter?
Developed by John Dalton: the theory that atoms are the fundamental building blocks of matter
Postulate 1:each element is made up of extremely small particles called atoms
Postulate 2:All atoms of a specific element are identical to one another in mass and other properties, but the atoms of one element are different from the atoms of all other elements.
Postulate 3: atoms are neither created nor destroyed in chemical reactions
Postulate 4: Atoms of more than one element combine to form compounds and a given compound always has the same relative number and kind of atoms.
Waves are characterized by their...
frequency (number of waves that pass through a particular point in one second)
wavelength (distance from crest to crest- or identical points- on successive waves)
Amplitude (vertical distance from the mid-line of the wave to the top of the peak or bottom of the trough)
Periodic table is organized by increasing....and the elements become less...
atomic number, metallic.
Polyatomic Ions and their charge
An ion (positively or negatively charged) composed of two or more atoms. Charge is hard to predicted and must be memorized (ex: Carbonate-CO3 has a negative 2 charge)
True or false: Molecular formula is used to determine Empirical formula
False: You need the reduced empirical formula in order to calculate the simplified molar mass. Then divide the actual mass by the empirical formulas molar mass to get a value, then multiply the subscripts of the empirical formula by that value.
Electrons were discovered by...
J.J. Thomson and his cathode rays...Streams of negatively charged particles were found to emanate from cathode tubes, which caused fluorescence.
The movement of electrons inside of atoms produces...
light and other electromagnetic radiation.
True or False: many nonmetal elements are gases at room temperature
true: they also are poor conductors of heat and electricity, are brittle, and don't have luster.
What does a Lewis (electron dot) structure consist of?
Elements Symbol like Na (to represent the nucleus) and dots surrounding it to represent it's valence electrons.
What are the 3 steps to determining a chemical formula?
1. find the percent composition of all elements
2. Convert this information into an empirical formula
3. find the molecular formula (the true number of atoms/ elements in the compound)
Who and what discovered the charge on the electron?
Robert Millikan and his Oil drop experiment
What are the different orbitals and how many electrons are in each?
There are 4 (s-2 electrons, p-6 electrons, d-10 electrons, f-14 electrons)
As you go across a period on the periodic table atomic radius ......
As you go down a column atomic radius....
decreases, increases
What is the Lewis Theory of Chemical Bonding?
A chemical bond (in lewis theory) involves the sharing or transfer of electrons to attain stable electron configurations for the bonding atoms.
If electrons are transferred, bond is ionic (Metal and Nonmetal).
True or False: You can round a 0.3 calculation for a subscript to 0
False you must multiple all the subscripts by a number which will make them whole numbers.
What was discovered by Ernest Rutherford?
Ernest Rutherford discovered the nucleus and the fact that the positive charge of an atom is concentrated in the nucleus. This was discovered through the Gold Foil Experiment.
What are the three principles/rules of electron configuration?
Aufbau Principle-Electrons must fill the lowest energy level/orbital before filling a higher energy level orbital.
Pauli Exclusion Principle-an orbital box can only hold two electrons of opposite spins
Hund’s Rule-Electrons of the same spin must spread out in an orbital level before pairing with an electron of the opposite spin.
What is ionization energy and what trends are shown in the periodic table?
The energy it takes to remove an electron from the outer shell. As you go down, decreases, as you go across increases (closer to stable configuration more energy required to take electron away).
What is the octet rule?
In chemical bonding, atoms share or transfer electrons to obtain a stable electron configuration which consists of 8 electrons in the outermost/valence shell.
What's another way to determine Chemical formula?
Combustion: If compound has H and C and CO2 and H2O are produced, those productions (measurements) can be used to determine percent composition as all C is converted to CO2 and all H is converted to H2O and these ratios (1molCO2=1molC, 1molH2O=2molH) are true
Regarding particles (like electrons) what quantities can be know?
The only quantity that can be known is the probability of an electron to occupy a certain space around the nucleus.
This configuration is used to simplify/shorten electron configurations
noble gas configuration
______is a trend directly proportional to Ionization energy.
Electronegativity: tendency of an atom to attract electrons (as you go down a column, it decreases, as you go across it increases)
What needs to be added when naming ionic compounds with transition metals?
Roman numerals to indicated the transition metal's charge.