Atomic Structure and the Periodic Table Flashcards
What is an atom?
The smallest part of an element that can exist
What is a proton?
A subatomic particle with a positive charge
What is an electron?
A subatomic particle with a negative charge
What is a neutron?
A subatomic particle with a neutral charge
Describe the charge of an atom
It is neutral, or has no overall charge, as the charges of the protons and electrons balance out
How do protons and electrons balance each other out?
The charges on each are the same size but opposite, so they cancel each other out
What does the atomic number of an element tell you?
it tells you the number of protons in one atom of that element - the atomic number is how you identify each element
What does the mass number tell you?
How many protons and neutrons there are total in the atom
What is an element?
A substance made up of only atoms with the same atomic number
What happens to atoms when they gain or lose electrons?
They become ions
What is an ion?
A charged particle that has either gained or lost electrons, making them cations or anions
What is an isotope?
A form of the same element with a different number of neutrons but the same number of protons.
What is relative atomic mass?
An average mass taking into account all the different masses and abundances of all the isotopes that make up the element
Why is relative atomic mass used?
Because many elements can exist as a number of different isotopes, so when referring to the element as a whole it is better to be representative
What is the equation to work out relative atomic mass?
What is a molecule?
2 or more atoms, held together by chemical bonds
What is a compound?
2 or more elements, held together by chemical bonds. They are always found in fixed specific proportions.
Can a molecule be a compound?
Yes, for example water is a molecule but is also a chemically bonded compound
Describe the properties of compounds compared to the original elements?
Normally, the properties of the compound are totally different to those of the elements that make it up
Describe the properties of mixture compared to the original elements?
The properties of a mixture are just a mixture of the properties of the separate parts of it
What is a mixture?
Two or more elements and/or compounds mixed together with no chemical bonds between them
What is chromatography used for?
It is used to separate compounds out of a mixture, e.g. to separate dyes out of an ink
How does chromatography work?
Each substance in the mixture moves up the chromatography paper at different rates specific to that substance, allowing us to identify each one
How does filtration work?
It traps an insoluble solid in the filter paper and allows the rest to past through
What are the two methods to separate soluble solids from solutions?
Evaporation and crystallisation
What is the process of evaporation?
Pour the solution into an evaporating dish and slowly heat it until the solvent starts to evaporate and the remaining solution becomes more concentrated. Continue the process until dry crystals are formed in the basin
What is the process of crystallisation?
Pour the solution into an evaporating dish and slowly heat until the solvent starts to evaporate, or until crystals start to form (point of crystallisation). Then remove the dish from the heat and leave it to cool. The salt should form crystals as it becomes insoluble in the cold concentrated solution. Filter the crystals out and leave them to dry
Why would you used crystallisation over evaporation and vice versa?
Evaporation is really quick, but can only be used if the salt doesn’t decompose when heated. This is when crystallisation is used, and crystallisation also produces bigger crystals
Describe how simple distillation works
The solution is heated and the substance with the lowest boiling point evaporates first. The vapour is then cooled, condenses in the condenser and collected.
What is a restriction of simple distillation?
You can only use it to separate things with very different boiling points
Compare the number of valence electrons of group 1, 7 and 0
Group 1 have one outer electron, group 7 have 7, and group 0 have 8 (except Helium has 2)
Compare the reactivity trend of groups 1, 7 and 0
Group 1 - increases going down the group
Group 7 - decreases going down the group
Group 8 - all very unreactive
What type of elements are found in group 1, 7 and 0?
Group one are metals, 7 and 0 are non-metals
What is the physical state of elements in group 1, 7 and 0 at room temp?
G1 - soft solids
G7 - Varies going down (F and Cl are gases, Br is liquid and I is solid)
G0 - all gases
Compare the densities of groups 1, 7 and 0?
G1 - low generally, but increases down the group
G7 - Varies, but generally low
G0 - Very low but increases down the group
Compare group 1, 7 and 0 in a reaction with water
Group 1 react vigorously, producing hydrogen gas and an alkali
Group 7 and 0 don’t react with water
Compare group 1, 7 and 0 in a reaction with oxygen
G1 - forms metal oxides
G7 - forms non-metal oxides
G0 - no reaction
Describe the formation of ions in G1, G7 and G0
G1 - Forms +1 ions by losing 1 electron
G7 - Forms -1 ions by gaining one electron
G0 - Does not form ions
Compare the bonding and compounds formed in groups 1, 7 and 0
G1 - forms ionic compounds with nonmetals
G7 - forms ionic with metals, and covalent with non-metals
G0 - rarely forms compounds
List some uses of group 1 elements
Batteries, fireworks, sodium lamps
List some uses of group 7 elements
Disinfectants, bleach, water treatment
List some uses of group 0 elements.
Neon lights, helium balloons, inert atmospheres
What is group 1 known as?
The alkali metals
What is group 7 known as?
The halogens
What is group 0 known as?
The noble gases
How and why did Mendeleev arrange his Periodic Table with gaps left open?
- he arranged them in terms of atomic mass and properties, because protons hadn’t been discovered (so not atomic number)
- For some elements he switched them across group numbers to better align with the trend in their chemical and physical properties
- He left gaps where he predicted undiscovered elements would fit, and predicted the atomic masses and properties of these missing elements
