Unit 1 Flashcards
What are the signs of a chemical reaction?
Chemical reactions are also known as chemical changes. There are many different ways to spot a chemical change. Five different signs include odor, temperature change, precipitate formation, production of gas bubbles, and a color change.
What is meant by the term ‘Rate of reactions’
The speed of a chemical reaction is affected by temperature, concentration, particle size and the presence of a catalyst. It can be calculated by measuring changes in reactants/products.
What does temperature do to the rate of reactions?
If the temperature is increased, the particles have more energy and so move quicker. Increasing the temperature increases the rate of reaction because the particles collide more often and with more energy. The higher the temperature, the faster the rate of a reaction will be.
What does concentration do to the rate of reactions?
If the concentration of reactants is increased, there are more reactant particles moving together. There will be more collisions and so the reaction rate is increased. The higher the concentration of reactants, the faster the rate of a reaction will be.
What does the size of a particle do to the rate of reactions?
By decreasing the particle size of a reactant, we are increasing its surface area. The greater the surface area, the higher the chance of collisions, thus the faster the rate of reaction. The smaller the particle size the faster the reaction.
What is a catalyst?
A catalyst speeds up the rate of a reaction but it is not used up in the reaction. If a catalyst is present, the reacting particles can collide more successfully with less energy and so the reaction can take place at a lower temperature.
How do you find the average reaction rate?
Delta(change in) Q(uantity) divided by Delta (change in) T(ime)
What is the unit you out for your answer to A.R.R.?
The unit that rate is measured in depends on the measurable quantity. Since a change in mass is measured in grams and a change in time in seconds in this example, the unit of rate would be grams per second (g s-1). Similarly, if a change in concentration is measured (in mol l-1), then rate will have the unit moles per litre per second (mol l-1 s-1) or a change in volume measured in cubic centimetres, centimetres cubed per second (cm3 s-1).
What is an atom made out of?
Atoms are made from protons, neutrons and electrons.
How is the periodic table arranged?
The periodic table arranges elements according to their atomic size and other properties.
What is an electron?
Negatively charged particles that spin around the positive centre of the atom in circles called energy levels. Their mass is so small it is nearly zero.
What is a proton?
Positively charged particles that are contained in the nucleus of the atom (the centre) they have a mass of 1 A.M.U. (atomic mass unit).
What is a neutron?
Particles with no charge that are also contained in the nucleus of the atom. They also have a mass of 1 amu.
What is the periodic table?
The periodic table brings order to information about the chemical elements. It helps chemists to understand why elements react as they do.
Main groups in the periodic table?
Alkali metals
The elements in group 1 are known as alkali metals. They react rapidly (very fast) with water, producing an alkaline solution and hydrogen gas. The metals become more reactive as you go down the group.
Halogens
The elements in group 7 are known as halogens. Fluorine and chlorine are gases. Bromine is one of only two liquid elements. Iodine is solid. They exist as diatomic molecules - they have two atoms in each molecule. As you go down the group the halogens become less reactive.
Noble gases
The elements in group 0 are known as noble gases. They are very unreactive and exist as individual atoms (monatomic).
Transition metals
The transition metals are elements which are found between groups 2 and 3. Well known examples are iron, copper and gold. They are generally quite dense (heavy) and many form brightly coloured compounds.
What is the atomic number?
The atomic number of an element tells you how many protons that the element has.
What does the electron arrangement mean?
The electron arrangement of all atoms can be found in the data booklet. All the electrons are arranged into energy levels. These energy levels can only hold a certain number of electrons.
The first energy level (the one nearest the nucleus) can hold a maximum of two electrons with the others being able to hold up to a maximum of 8 electrons (only true for the first 20 elements).
Mass Number
P(rotons)+N(eutrons)
What is an isotope?
Isotopes are atoms with the same atomic number but different mass number. (Different number of neutrons.)
What is a covalent bond?
A covalent bond, also called a molecular bond, is a chemical bond that involves the sharing of electron pairs between atoms.
What is a diatomic molecule?
A diatomic molecule is a molecule containing only two atoms. There are seven diatomic elements that you have to remember and a simple mnemonic to help with this. If you remember “Have No Fear Of Ice Cold Bear” then you will have remembered that the seven diatomic elements are Hydrogen, Nitrogen, Fluorine, Oxygen, Iodine, Chlorine and Bromine.
What are the two types of covalent bonding?
Molecular and network.
What is ionic bonding?
Ionic bonding is a type of chemical bonding that involves the electrostatic attraction between oppositely charged ions.
What groups will loses electrons and what group gains electrons?
An atom of Group 1-3 will lose an electron and form a positive ion.
An atom of Group 5-7 will gain an electron and form a negative ion.
What does an ionic compound form?
Ionic compounds form what is known as a lattice structure.
Why do ionic compounds only conduct electricity as a solution?
Ionic compounds dissolve in water easily, when they do this their lattice breaks up completely and water molecules surround the separated ions. Therefore they can conduct as their ions are free to move.
Name facts about an ionic lattice:
All ionic lattice structures have a high melting point and boiling point because many strong ionic bonds need to be broken.
They conduct when molten or in solution as the ions are free to move.
They can be broken down by electrolysis. They are generally soluble in water.
Name facts about a covalent molecular structure:
They have low melting points and boiling points because the attractions between molecules are easy to overcome.
They do not conduct electricity because there are no free charges to move.
Some covalent molecular compounds have higher melting points than expected.
Most do not dissolve in water but may dissolve in other solvents.
Name facts about a covalent network structure:
All covalent network structures have very high melting points and boiling points because many strong covalent bonds need to be broken.
They are all hard, and do not conduct electricity because there are no free charges that can move.
They do not dissolve.
The definition of soluble
Able to be dissolved.
Definition of a solvent
Able to dissolve other substances
Definition of a solute
Can be dissolved in a solvent
What are the prefixes for elements?
Mono- (one) Di- (two) Tri- (three) Tetra- (four) Penta- (five) Hexa- (six)
What does each suffix mean?
- ide (two elements)
- ite (three elements, one including Oxygen)
- ate (three elements, one including Oxygen)
What is valency?
Valency is the combining power of an element. Elements in the same group of the periodic table have the same valency. The valency of an element is related to how many electrons are in the outer shell.
What are group ions?
Group ions contain two or more atoms and usually have a negative charge.
Formula using roman numerals:
I - 1 II- 2 III- 3 IV- 4 V- 5 VI- 6 They can be used in the S.V.S.D.F.
What does the initials of S.V.S.D.F mean?
S(ymbols) V(alency) S(wap) D(ivide) F(ormula)
What is a balanced equation?
A chemical equation is said to be balanced when there are the same number of the same type of every atom on both sides of the equation.
How do you calculate concentration?
C=N(moles)xV(olume in litres)
How do you calculate mass?
Mass=Moles(N)xGram Formula Mass
How do you calculate moles?
N=C÷V(litres) or N=Mass÷Gram Formula Mass
How do calculate % mass of an element?
% mass= (Mass of desired element÷GFM)x100
What is G.F.M. in consideration of 1 mole?
The G.F.M. of a compound is One mole of that compound.
What is a Mole?
6.02x10 to the power of 23
What is the pH meter?
The pH scale measures the acidity or alkalinity of a solution. A pH less than 7 is acidic. Alkalis dissolve in water to give a pH greater than 7. A pH equal to 7 indicates a neutral solution.
What’s an acid’s pH?
<7
What’s an alkali/base’s pH
> 7
What is water’s pH?
7
What is an Alkali?
Alkalis are soluble bases. Soluble metal oxides produce alkalis when dissolved in water.
What is an acidic solution?
An acidic solution can be formed when a non-metal oxide is dissolved in water.
Why can acids and alkalis solutions conduct electricity?
Acidic and alkaline solutions can conduct electricity because they have ions that are free to carry charge. Acids have H+ ions. Where alkalis have OH- ions.
What is neutralisation?
Neutralisation is the reaction of an acid with a base that results in the pH moving towards 7.
How do you name salts?
To name the salt, the metal ion from the alkali (or base) replaces the hydrogen ion from the acid - (alkali to front, acid to back). For example:
Hydrochloric acid+Sodium Hydroxide ——>Sodium Chloride + Water.
For Metal carbonates + Acid ——–> Salt+Water+Carbon Dioxide
What does (aq), (l), (g), (s)?
aq= Solution
l=liquid
g=gas
s=solid
What is a spectator ion?
A spectator ion is an ion that exists as a reactant and a product in a chemical equation.
What is a titration?
A titration experiment can be carried out to accurately measure the volume of substances that react in chemical reactions.
This technique is commonly used in neutralisation reactions and can also be used to calculate an unknown concentration (of either the acid or alkali).
What is an endothermic reaction?
A chemical reaction that takes in energy from its surroundings.
What is an exothermic reaction?
A chemical reaction which gives out heat or light energy
