Section 1 - Key Concepts in Chemistry Flashcards
What do Chemical Equations show?
Chemical Changes.
What are three ways to write a Chemical Equation?
Symbol Equations, Ionic Equations and Chemical Equations.
What do Symbol Equations do?
They show the atoms on both sides of the equation.
What must any Symbol Equation be?
Balanced, the same number of atoms on either side.
What are the four State Symbols? What do they mean?
(s) - Solid
(l) - Liquid
(g) - Gas
(aq) - Aqueous
What do State Symbols tell you?
The state of a substance in an equation.
What do Word Equations do?
They simplify things by only stating the name of any substance in a reaction.
What is the formula of Water?
H₂O
What is the formula for Ammonia?
NH₃
What is the formula for Carbon Dioxide?
CO₂
What is the formula for Hydrogen?
H₂
What is the formula for Chlorine?
Cl₂
What is the formula for Oxygen?
O₂
What is the ionic formula for Ammonium?
NH₄⁺
What is the ionic formula for Hydroxide?
OH⁻
What is the ionic formula for Nitrate?
NO₃⁻
What is the ionic formula for Carbonate?
CO₃²⁻
What is the ionic formula for Sulfate?
SO₄²⁻
What do Ionic Equations do?
Display only the reacting particles in any reaction occurring in solution.
What is a Hazard?
Anything with the potential to cause harm or damage.
What are the six common Hazard Symbols?
Oxidising Harmful Environmental Hazard Toxic Corrosive Highly Flammable
What is the Oxidising Symbol and what does it mean?
A circle on fire, it means the chemical provides Oxygen allowing other materials to burn more fiercely.
What is the Harmful Symbol and what does it mean?
An exclamation mark, it means it can cause irritation, blistering or reddening of the skin.
What is the Environmental Hazard Symbol and what does it mean?
A dead fish under a dead tree by a lake, it means it is harmful to organisms and the environment.
What is the Toxic Symbol and what does it mean?
A skull and crossed bones, it means it can cause death by swallowing, breathing it in or otherwise.
What is the Highly Flammable Symbol and what does it mean?
A flame, it means the thing catches fire quickly.
What is the Corrosive Symbol and what does it mean?
Two vials with one dripping on a table and the other on a hand, both are slightly corroded, it means that it destroys materials including living material.
What are Atoms?
The tiny particles that make up everything in the universe.
What was the Plum Pudding model? who made it? When?
The model of the atom that describes Atoms as solid positively charged spheres, like a pudding, with small negatively charged electrons in it, like the plums, it was made by John Dalton in the early 1800s.
What was the Rutherford model? Who made it? When?
The first model of the atom to state that atoms are mostly empty space, and that atoms had a “cloud of electrons surrounding a tiny nucleus, it was made by Ernest Rutherford in 1909.
Who disproved the Plum Pudding Method? When? How?
Ernest Rutherford and his students, Hans Geiger and Ernest Marsden, conducted the gold foil experiment in 1909, they shot alpha particles at a sheet of gold foil, most passed through the empty space though some deflected of the nucleus.
What is the Bohr Model? Who made it?
When scientists realized the “cloud” of electrons in the Rutherford Model would collapse because the electrons would be attracted to the nucleus, it was proposed the electrons could be contained in shells, orbiting the atom in specific fixed energy levels. This was suggested by Neils Bohr.
What are the names of the subatomic particles that make up atoms?
Protons, Neutrons and Electrons.
What is relative mass?
A measure of mass where a proton or neutron equals 1.
What is the relative mass of an electron?
0.0005
What is the relative charge of an electron?
-1
What is the relative charge of a neutron?
0
What is the relative charge of a proton?
+1
What is the nucleus?
The center of an atom, it contains protons and neutrons.
What is the difference between atoms and ions?
Atoms are neutral, ions are charged.
What are the two types of ion? What is their charge?
Cations, which are positive, and anions, which are negative.
What are Isotopes?
A different form of the same element, meaning it has the same number of protons but a different number of neutrons.
What is relative atomic mass?
An elements average mass of one atom compared to 1/12th the mass of a Carbon-12 atom.
How is relative atomic mass represented in equations?
Aᵣ
How is relative atomic mass worked out by isotopic abundances?
Multiply each isotope’s atomic mass by their isotopic abundance, add up the results, divide the total by the sum of the abundances.
Which groups of the periodic table are most likely to form ions?
1, 2, 6 and 7
How is an ion’s charged worked out?
By how many electrons it needs to gain/ lose in order to have a full outer shell.
What are the three types of bonding?
Ionic, covalent and metallic.
How does Ionic Bonding work.
The ions have opposite charges and are drawn to each other to become neutral.
What are the characteristics of materials made by Ionic Bonding?
The bond is between a metal and a non-metal, the product is known as a salt, the bond is very strong, giving a high melting and boiling point, most Ionicly bonded materials are soluble in water, they are non-conductive as solids but in solution or molten form they conduct.
How can Ionic bonded be displayed as a diagram?
Dot and Cross Diagrams.
What type of structure do Ionic Compounds form?
A regular lattice.
What are the different models for representing compounds?
Ball and Stick models, 3D models, Dot and Cross Diagrams, Displayed formulas.
What is the benefits and limitations of 2D representations?
They are simple and clearly display how the atoms are connected, but don’t show the shape of the substance or the size of the atoms so it has no sense of scale.
What are the benefits and limitations of Dot & Cross Diagrams?
They are useful for showing how compounds or molecules are formed and where the electrons came from, but don’t usually show the sizes of atoms or ions, nor how they’re arranged.
What are the benefits and limitations of 3D models?
They show the arrangement of Ions, but only the outer layer of the substance.
What are the benefits and limitations of Stick diagrams?
They show how the atoms or ions in a substance are connected, help visualize structures and are more realistic but they often aren’t to scale and can be misleading as the large gaps between atoms or ions is where the electrons would be interacting.
How does Covalent bonding work?
Two atoms share pairs of electrons with one another, completing each other’s outer shell.
What are common characteristics among most covalently bonded compounds
They make simple molecular structures, the atoms are held together with strong covalent bonds but the molecules are held together by weak intermolecular forces, giving them low melting and boiling points, most are a gas at room temperature, the larger the molecules are the stronger the intermolecular forces and their melting and boiling points, they are non-conductive, solubility varies.
What are Polymers?
Long chains of covalently bonded carbon atoms.
What are the six very common simple molecular substances?
Hydrogen, Hydrogen Chloride or Hydrochloric acid, Water, Oxygen, Methane and Carbon Dioxide.
What are giant covalents?
Large covalently bonded structures.
What are common characteristics of most giant covalents?
The atoms are bonded together by strong covalent bonds, very high melting points, insoluble, non-conductive, durable.
What are the three most common examples of giant covalents?
Diamond, Graphene and Graphite.
What makes graphene and graphite different to most giant covalents?
They are conductive.
What are Fullerenes?
Molecules of covalently bonded carbon that form either a closed tube or hollow ball.
What are two examples of fullerenes?
Buckminsterfullerene and Carbon Nanotubes
What are common characteristics of most fullerenes?
Mainly made of hexagons of covalently bonded atoms, but often incorporate pentagons or heptagons, can cage other molecules, have large surface areas.
What are some uses of diamonds?
Industrial tools, jewellery and heat syncs.
What are some uses of graphene
Building reinforcement,heat syncs, capacitors and batteries.
What are some uses of graphite?
Pencils, electrodes and lubrication.
What are some uses of fullerenes?
Drug delivery and tennis rackets.
How does metallic bonding work?
The electrons in the outer shells are delocalised, this means there is a strong electromagnetic attraction between the positive metal ions and the negative electrons, this holds the atoms together very securely.
What are common properties of metals?
High melting points, shiny, insoluble, very dense, malleable, conductive of electricity and heat.
What is conservation of mass?
In reaction no atom is created or destroyed.
If mass increases in a reaction what has happened?
One of the reactants was a gas and the products were heavier than the solid, liquid and aqueous reactants.
If mass decreases in a reaction what has happened?
One of the products was a gas and left the system after the reaction, meaning it wasn’t measured.
What is relative formula mass?
The mass of a formula compared to 1/12 the mass of a carbon-12 atom. It is also the relative atomic masses of all the atoms in the formula added together.
What are empirical formulae?
The simplest ratio of atoms in a formula.
What is Avogadro’s constant?
6.02 x 10²³
What is a mole?
An Avogadro’s constant of that substance.
What does a mole weigh?
The same number of grams as the thing’s relative atomic mass or formula mass.
How is relative formula mass written in a formula?
Mᵣ
What is the formula to work out moles from mass?
Number of moles = mass/ Mᵣ or Aᵣ
What is concentration?
How much is of something dissolved into something else.
What is a solvent?
A thing that can dissolve other things
What is a solute?
A thing that is being dissolved.
What is the equation for concentration?
C= m/V
C = concentration m = mass V = volume
What is Volume measured in for concentrations.
dm⁻³
How can litres and cm³ be converted into dm⁻³
1 dm⁻³ = 1 Litre = 1000 cm³
What is a limiting reactant?
A reactant that is used up and preventing the reaction from continuing.
