General Review -- Definitions Flashcards
Molar mass
The mass of ONE mole of a substance
It’s the mass given of each element on the periodic table.
Units for molar mass
g/mol
Avogadro’s number units
mol
Therefore one mole is 6.02 x 10^23 molecules.
Why measure in moles?
“Scientists use moles because moles are an easy and consistent way to work with large numbers of particles. In addition, using moles ensures that comparisons are being made between equal numbers of atoms or molecules. Using grams in calculations instead of moles would be unwieldy and confusing.”
- https://study.com/academy/lesson/how-to-convert-grams-to-moles.html#:~:text=Scientists%20use%20moles%20because%20moles,would%20be%20unwieldy%20and%20confusing.
The law of definite proportions
the elements in a chemical compound are always present in the same proportion by mass
Empirical formula
The lowest whole number ratio of atoms in a substance.
E.g. CH2, C2H4, and C4H8 all contain the same ratio of hydrogen compared to carbon. The simplest
Law of conservation of mass
mass/matter is neither created nor destroyed in chemical reactions
Coulombs Law
Like charges repel while unlike charges attract (protons and electrons).
The larger the charge, the more it will either attract or repel.
The closer in distance unlike charges are to each other, the greater the force of attraction between them while the farther they are apart, the weaker the force of attraction.
Also, the closer like charges are the greater the force of repulsion and vice versa.
Isoelectronic –
Same number of electrons–I think.
SEARCH THIS UP TO MAKE SURE AND ALSO SEARCH UP WHY THIS IS USEFUL.
Coulombs Law
- Like charges repel while unlike charges attract (think protons and electrons)
- The larger the charge, the more it will either attract or repel
- The closer in distance unlike charges are to each other, the greater the force of attraction between them, while the farther they are apart, the weaker the force of attraction.
- Also, the closer like charges are, the greater the force of repulsion and vice versa.
Period VS. Group & other names for them
Period = row
Group = column, family
What is shielding?
“Electrons in filled energy levels between the nucleus and outer shell electrons shield the outer shell electrons somewhat from the effect of protons in the nucleus.”
In the same energy level, the shielding is the same.
The more energy levels between the nucleus and the outer electrons, the more shielding and the outer electrons are less attracted to the nucleus.
Effective Nuclear Charge, (Zeff)
Effective nuclear charge, Zeff, is the net force of attraction between the electrons and the nucleus of the atom. It considers both the attractiveness of the nucleus, the energy level of the valence electrons and the shielding of valence electrons by core electrons.
We say that an atom such as Cl has a greater effective nuclear charge than Si since, even though the valence electrons are on the same energy level and amount of shielding is the same, Cl has MORE protons in the nucleus.
Electronegativity
The electronegativity is the ability of an individual atom, when bonded to attract bonding electrons to itself.
What happens to the distance between particles when the temperature increases? (Kinetic Molecular Theory)
They get farther apart. As in, because the particles are moving faster, the volume of the gas expands, and and the particles are farther apart.
- If the gas is in a confined volume, heating it up could make it explode.
Metallic Bonds
This type of covalent bonding specifically occurs between atoms of metals, in which the valence electrons are free to move through the lattice.
The electrons move freely is the key point here.
London-Dispersion Forces
All molecules (covalent compounds) are held together in whole or in part by LDF. Even if they contain dipole-dipole or hydrogen bonding (LDF will just play a less significant role).
LDF are weaker forces that occur between two different atoms of two different molecules.
They are created by momentary (temporary/instantaneous) dipoles.
The more electrons you have, if they all shift to one side, it will make a bigger LDF.
Dipole-dipole forces
Dipole-dipole forces exist only between polar molecules, they contain permanent dipoles.
They occur when the slightly positive side of one molecule is attracted to the slightly negative side of another molecule. This force of attraction is the intermolecular dipole-dipole interaction.
Hydrogen bonds
Hydrogen bonds are a special type of intermolecular force. It is a very strong dipole-dipole force that occurs between hydrogen and another very electronegative atom, usually F, O, or N.
(Hydrogen just wants to have FON!)
It is a VERY STONG dipole-dipole force.
Metal Oxide and Water equal what?
Basic solution because the product is a metal hydroxide which is a type of base.
E.g.
CaO + H2) –> Ca(OH)2
- Calcium Hydroxide
Non-Metal Oxide and Water equal what?
Acidic solution (Adic.).
E.g.
SO3 + H2O –> H2SO4
- Sulphuric acid
Molarity
Moles/Litre
