Intro to Chemistry & Moles/Mass Flashcards
What is Chemistry?
The study of matter.
What is the equation for moles?
Moles = Mass (g) / Molar Mass
What is Avogadro’s Number?
6.02*10^23
What is a Mole?
One mole is the Avogadro’s number of particles in a substance.
What are the types of chemical reactions?
Combination Decomposition Single displacement/replacement Double displacement/replacement Combustion
What is Combination?
Two or more elements combined to make one compound.
A + B - AB
What is decomposition?
The opposite of combination where one compound breaks down into elements or separate compounds.
AB - A + B
What is single replacement?
One element replaces another one in a compound.
A + BC - B +AC
What is double replacement
Two elements in two compounds switch places.
AB + CD = AD + BC
What is combustion?
Oxygen combines with a compound to give carbon dioxide and water. This is an exothermic reaction, meaning heat is given off.
AB + O2 = CO2 + H20
What are the indicators of a reaction?
Emission of light or heat, Formation of a gas, Formation of a precipitate, Change in colour Emission of odour
How do you calculate moles from mass (g)
Mass/Molar Mass
How many moles in 58.8g NaCl?
Moles = Mass / Molar Mass
Molar mass for Na = 23
Molar mass for Cl = 35.5
Molar Mass for NaCl = 23 + 35.5 = 88.5g/mol
58.8g (Mass) / 88.5 (molar mass) = 1 Mole
How many moles in 4g NaOH?
Moles = Mass / Molar Mass
Molar Mass of NaOH = 40g/mol (23 + 16 + 1)
4g/40 = 0.1 mole
How many grams in 1.5 mole CO2?
Moles = Mass / Molar Mass
Mass = Moles * Molar mass
Molar mass of CO2 = 44g/mol (12 + 162)
1.544 = 66g
What is Daltons Atomic Theory?
. All matter is made of tiny particles called atoms
. A given element has similar atoms and different to atoms from different elements
. Two or more elements combine to make a compound. A particular compound always has the same kind of atoms and always has the same number of each kind of atom
. A chemical reaction involves the rearrangement, separation or combination of atoms. Atoms are never created nor destroyed.
What is the atomic weight (mass)?
Number of protons + number of electrons
What is an isotope?
An element with the same number of protons but different numbers of neutrons.
What are electron energy levels?
Each electron has a specific energy known as an energy level. All the electrons with the same energy are grouped into the same energy level. Each energy level is assigned with a number (n) beginning with n-1, n=2, up to n=7.
What is Quantum Mechanics?
Describes the arrangement of atoms in terms of:
- main or principle energy levels
- energy subshells
- Orbitals (space occupied within the atom)
What is the principle energy level?
Contains elements that are:
- Close in energy
- Similar distances to the nucleus
- Have values of 1,2,3,4,5,6….
- Maximum number of electrons are 2n^2
What are energy levels (shells)?
A group of electrons with the same principle quantum number (n).
The first shell (n=1) has the lowest energy level then shell 2 and so on.
The maximum number of electrons per shell is 2n^2.
What are energy subshells?
Sub energy levels within energy levels. All the electrons in the subshell have the same energy. Designated s,p,d,f.
Sublevel energy = s<p></p>
What is electron configuration?
List of sub shells containing electrons. In order from lowest to highest energy levels. Number of electrons are shown by the superscript.
What are quantum numbers?
Quantised values to describe the electrons in an atom. They are 4 quantum numbers represented by letters n, l, Ml, Ms. These are the Principle Quantum Number, Angular Momentum Quantum Number, Magnetic Quantum Number and Spin Quantum Number.
The principle quantum number (n).
n represents the main energy of an electron. Allowable values are n = 1, 2, 3, 4,…
maximum electrons per energy level = 2*(n^2)
Electrons with higher n level have more energy.
What is the calculation for moles to particles and particles to moles?
From moles to particles = moles * Avogadro’s number (6.02*10^23)
From particles to moles = particles / Avogadro’s number
What is molar mass?
The mass of one mole of a substance. In grams.
What is the periodic table
Shows all of the known elements in one table.
The periodic table lists the elements in increasing atomic number in rows (periods). Lists the elements with similar chemical properties in groups. These elements have similar properties as they have the same number of outer electrons.
Group trends.
As we increase the atomic number or go for up to down, each atom has another energy level so they get bigger. As we go left to right, atoms get smaller and have the same energy level. However there is more nuclear charge. Also the outer electrons are pulled closer.
Ionisation?
The amount of energy required to remove one electron. Removing one electron makes a +1 ion. The further down we go a group, the further the electrons are from the nucleus, plus the more electrons an atom has thus low electronegativity (ability to attract a bonding pair)
Angular Momentum Quantum Number (l).
Describes the subenergy level the shape of the orbitals within the sublevels. Allowable values for l are from 0 all the way to n-1. For example of n=3, l = 0, 1 & 2 (n=3-1=2).
Each of these values represents a sub level.
If l = 0 - s orbital
1 - orbital
2 - orbital
3 - orbital
Magnetic Quantum Numbers (ml)
Describe the number of orbitals. ml values are between –l and +l including 0. For example if l = 2, ml = -2, -1, 0, +1, +2. So d orbital has 5 orbitals with a total of 10 electrons (5 orbitals with 2 electrons each).
Spin Quantum Number (ms)
Describes that 2 electrons in the same orbital have opposite spin values, -0.5 and +0.5. These are shown as the half up and half down arrows in electron config diagrams.
