Module 2: Foundations In Chemistry Flashcards
What three subatomic particles are atoms made up of?
- Protons
- Neutrons
- Electrons
What is the mass and relative charge of a proton?
Mass: 1
Charge: +1
What is the mass and relative charge of neutrons?
Mass: 1
Charge: 0 (neutral)
What is the mass and relative charge of electrons?
Mass: 1/2000
Charge: -1
What is the mass number?
The larger number on the periodic table. The number of protons + neutrons in an atom.
What is the atomic number?
The smaller number on the periodic table. The number of protons.
What are Isotopes?
atoms of the same element with different numbers of neutrons.
Do isotopes of the same atom have the same chemical properties and the same physical properties? Explain why.
They will have the same chemical properties as they have the same electronic structure.
However may have different physical properties due to different masses.
What are Ions?
Atoms that have lost or gained electrons.
What is meant by Relative Atomic Mass?
The weighted mean mass of an atom compared with 1/12 the mass of one atom of carbon-12
What is meant by Relative Isotopic Mass?
The weighted mass of one atom of an isotope compared with 1/12 the mass of one atom of carbon-12.
How to calculate relative atomic mass from isotopic abundances?
Multiply each relative atomic mass by its % relative isotopic abundance and add the results, then divide by 100.
What is the name and the charge of the molecule NH₄?
ammonium forms a +1 molecular ion
What is the name and the charge of the molecule OH?
Hydroxides form -1 molecular ions.
What is the name and the charge of the molecule NO₃?
Nitrates form -1 molecular ions.
What is the name and the charge of the molecule CO₃?
Carbonates form -2 molecular ions.
What is the name and the charge of the molecule SO₄?
Sulphates form -2 molecular ions.
How do you work out an ionic formula from the ionic charges?
In an ionic compound, the overall charge is zero. Therefore, the ions in the compound must balance to zero, so you can add more + or - ions to balance the charges.
What do the state symbols (s), (l), (g), (aq) represent?
(s): solids
(l): liquids
(g): gas
(aq): aqueous
What is the rule for significant figures?
Round the result to the lowest amount of significant figures in the question.
How do you convert between Celcius and Kelvins?
Celsius + 273 = Kelvins
What is 1dm in cm?
1 dm = 10cm
How to convert between cm³ and m³?
cm³ / 1 000 000 = m³
What is the definition of ‘a mole?’
A mole is the amount of a substance that contains the same number of particles as the number of carbon-12 atoms in 12g.
What does Avogadro’s number represent?
The number of particles in a mole.
What is the equation for moles?
Moles = Mass (g) / Molar Mass (g mol -1)
How to figure out the number of particles in a substance?
No. of particles = No. moles x Avogadro’s constant.
What is the Molar Gas Volume at room temperature and pressure?
24 dm³
What is the equation for ideal gas law?
PV = nRT
pressure (Pa) x volume (m³) = mols x gas constant (J/kmol) x temperature (K)
Two equations for the concentration of solutions?
concentration (g dm⁻³) = mass (g) / volume (dm³)
concentration (mol dm⁻³) = mol / volume (dm³)
What is meant by the term ‘Molecular Formula?’
The actual number of atoms in a compound.
What is meant by the term ‘Empirical Formula?’
The simplest whole number ratio of atoms in a compound.
What does it mean if a crystalline structure is ‘hydrated?’
Contains water molecules.
What does it mean if a substance structure is ‘anhydrous?’
The substance contains no water molecules.
How do you calculate percentage yield?
% Yield = ( Amount of product, in mol / theoretical amount of product, in mol) x 100
What are some of the reasons for a lower than predicted yield in reactions?
- The reaction may not go to completion.
- Unpredicted side reactions may occur.
- The reactants may not be pure.
How to calculate Atom Economy?
% Atom Economy = (molar mass of useful products / sum of molar mass of all products) x 100
How can Atom Economy be improved?
Alternative reaction pathways
Finding uses for waste products.
What is the formula and ions in Hydrochloric Acid?
HCl (g)
H⁺(aq) + Cl⁻(aq)
What is the formula and ions of Sulphuric Acid?
H₂SO₄ (l)
H⁺(aq) + HSO⁴⁻(aq)
What is the formula and ions of Nitric Acid?
HNO₃
H⁺(aq) + NO³⁻(aq)
What is the formula and ions of Sodium Hydroxide?
NaOH
Na⁺ and OH⁻
What is the formula and ions of Potassium Hydroxide?
KOH
K⁺ and OH⁻
How can you tell if an acid is strong or weak?
Strong acids fully dissociate, to release H⁺ ions, in aqueous solutions. Weak acids partially dissociate.
What is the (template) Neutralisation Equation?
H⁺ + OH⁻ (reversible reaction arrow) H₂O
Metal + Acid -> ?? + ??
Metal + Acid -> Salt + Hydrogen
Metal Oxide + Acid -> ?? + ??
Metal Oxide + Acid -> Salt + Water
Metal Hydroxide + Acid -> ?? + ??
Metal Hydroxide + Acid -> Salt + Water
Metal Carbonate + Acid -> ?? + ?? + ??
Metal Carbonate + Acid -> Salt + Water + Carbon Dioxide
What is the oxidation state of all uncombined elements?
0
TRUE OR FALSE
The sum of oxidation states in an ion is equal to the charge on that ion?
TRUE
What is the usual oxidation state of Oxygen and what are the exceptions?
Usually -2, except in peroxides when it is -1 and when bonded with Fluorine when it is +2.
What is the usual oxidation state of combined hydrogen and what are the exceptions?
Usually +1, except in metal hydrides where it is then -1.
What is the oxidation number in combined Fluorine?
Always -1
What is the usual oxidation state for combined Group 1 elements?
+1
What is the usual oxidation state for combined Group 2 elements?
+2
What is Oxidation?
What is Reduction?
Oxidation: The loss of electrons.
Reduction: The gain of electrons.
What is a Redox Reaction
A reaction in which both oxidation and reduction take place.
What does an increase in oxidation states tell us?
What does an decrease in oxidation states tell us?
Increase: Oxidation (Gain of electrons).
Decrease: Reduction (Loss of electrons).
What is a disproportionation reaction?
The oxidation and reduction of the same element in a redox reaction.
What do you balance these things with in redox reaction half equations?
oxygen
hydrogens
charges
Oxygen: H₂O
Hydrogen: H⁺
Charges: e⁻
What sub-shell is in the first shell?
1s
What sub-shells are in the second shell?
2s and 2p
What sub-shells are in the third shell?
3s, 3p and 3d
What sub-shells are in the fourth shell?
4s, 4p, 4d and 4f
What is the order of sub-shells 1-4 in order of increasing energy?
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 4d, 4f
How many electrons can ‘s’ sub-shells hold?
2
How many electrons can ‘p’ sub-shells hold?
6
How many electrons can ‘d’ sub-shells hold?
10
What is Ionic Bonding?
The electrostatic attraction between a metal and a non-metal: resulting in a positive, metal ion and negative, non-metal ion.
Properties of Giant Ionic Structures and why?
(hints: m.p. b.p., s, e)
- High melting and boiling points due to strong electrostatic attractions.
- Soluble in polar solvents (such as water) as the polar charges attract oppositely charged ions, disrupting the lattice.
- Conduct electricity when molten/dissolved as the solid lattice breaks down and ions are free to move, allowing them to carry electrical charges.
What is Covalent Bonding?
The sharing of electrons between two non-metals.
What is Dative Covalent Bonding?
How are these bonds represented?
When one element gives both electrons for the covalent bond.
Represented using an arrow pointing from the element giving the bonding pair.
What is the name of the shape and bond angle in a molecule with one/two bonding pairs and no lone pairs?
Name: Linear Molecule
Angle: 180*
What is the name of the shape and bond angle in a molecule with three bonding pairs and no lone pairs?
Name: Trigonal Planar
Bond Angle: 120*
What is the name of the shape and bond angle in a molecule with four bonding pairs and no lone pairs?
Name: Tetrahedral
Bond Angle: 109.5*
What is the name of the shape and bond angles in a molecule with five bonding pairs and no lone pairs?
Name: Trigonal Bipyramidal
Bond Angles: of 120* and 90*
What elements always obey the octet rule?
Carbon, Nitrogen, Oxygen and Fluorine.
What is the name of the shape and bond angles in molecule with six bonding pairs and no lone pairs?
Name: Octahedral
Angles: 90*
What is Electron-Pair Repulsion Theory?
Electrons repel each other, so the electrons on the outer shell arrange each other so they are as far apart as possible.
What is Electronegativity?
The power of an atom to attract the two electrons in a covalent bond.
Does electronegativity increase or decrease across a period? Why?
Electronegativity increases as the nuclear charge increases (due to higher atomic number = the number of protons increasing)
Does electronegativity increase or decrease down a group? Why?
Electronegativity decreases as there is an increase in electron shielding and atomic radius increases.
What is a Permanent Dipole?
A slight charge difference across a bond caused by a difference in the electronegativities of the bonded atoms.
What are Intermolecular Forces?
Forces between molecules.
What is a Permanent Dipole-Induced Dipole Interaction?
When a molecule with a permanent-dipole goes near a non-polar molecule, it causes the electrons in the shell of the non-polar molecule to shift slightly and become slightly polar. The polar molecule having induced the non-polar molecule.
What is a Polar Covalent Bond?
A covalent bond that has a permanent dipole.
What are London (dispersion) Forces?
Very weak attractive forces between induced dipoles.
What is an Instantaneous Dipole?
A dipole that will occur at a random moment in a usually non-polar molecule because electrons are constantly moving.
What is Hydrogen Bonding?
A strong permanent dipole-permanent dipole attraction between:
- An electron deficient hydrogen atom bonded with another atom
…and…
- A lone pair of electrons on a highly electronegative atom bonded with another atom.
What are the effects of hydrogen bonding on the properties of water and why?
- Ice is less dense than water as hydrogen bonds pushes molecules further apart.
- Water has a higher than expected melting point and boiling point as hydrogen bonds are stronger than most intermolecular forces.
Properties of Simple Molecular Structures?
- Low melting and boiling points
- Insoluble in water
- Does not conduct electricity
What is a Sigma (𝝈) Bond?
A bond that results from a direct overlap of two orbitals on the bonding atoms.
How do you draw a bonding diagram of a 3D molecule?
straight line: bonds in tehe plane of the paper.
dotted wedge: bond going ‘out’ of the page.
bold wedge: bond going ‘into’ the page.
What is a Pi (π) Bond?
A bond that results from the sideways overlap of two p-orbitals on two bonding atoms.
What is meant by the term ‘ionic lattice?’
A repeating pattern/structure of positive and negative ions.
What is meant by ‘Molar Gas Volume?’
The volume occupied by one mole of any gas a constant temperature and pressure.
Equation for Dilutions
C1V1 = C2V2
C = concentration
V = volume
