Paper 1 - Topic 1, Atomic Structure And The Periodic Table Flashcards
Describe the nucleus
- In the middle of the atom
- Contains protons and neutrons
- Has a positive charge (because of protons)
- Almost the whole mass is concentrated in the nucleus
Describe Electrons
- Move around the nucleus in electron shells
- They’re negatively charged and tiny
- Electrons have virtually no mass
Why is an atoms overall charge neutral
- they have the same number of protons as electrons
- the charge on the electrons is the same size as the charge on protons, the charges cancel each other out
What does the atomic number tell you
How many protons there are in
What does the mass number tell you
The total number of protons and neutrons in the atom
How do you work out the number of neutrons
Mass number - atomic number
What is an isotope
Isotopes are different forms of the same element, which have the same number of protons but a different number of neutrons (same atomic number but different mass number)
What is the relative atomic mass (Ar)
An average mass taking into account the different masses and abundances of all isotopes that make up an element
What is the formula for relative atomic mass
Sum of (isotope abundance x isotope mass number)
—————————————————————————
sum of abundance of all the isotopes
What is a compound
- Substances formed from two or more elements, the atoms of each are in fixed proportions throughout the compound and held together by chemical bonds
- usually difficult to separate the original elements of a compound out again - need a chemical reaction
What is ionic bonding
- Compound which is formed from a metal and a non-metal
- metal atoms lose electrons to form positive ions
- non-metal atoms gain electrons to form negative ions
- the opposite charges mean that the ions are strongly attracted to each other
What is covalent bonding
- a compound formed from non-metals consists of molecules
- each atom shares an electron with another atom
What is the formula for ammonia
NH3
What is the formula for sodium chloride
NaCl
What is the formula for carbon monoxide
CO
What is the formula for Hydrochloric acid
HCl
What is the formula for calcium chloride
CaCl2
What is the formula for sodium carbonate
Na2CO3
What is the formula for sulfuric acid
H2SO4
What is the definition of mixture
A mixture is made from two or more elements or compounds being mixed together, without the formation of any chemical bonds. They can be separated using techniques like filtration, crystallisation, simple distillation, fractional distillation and chromatography
How do you do paper chromatography
- Draw a line near the bottom of a sheet of filter paper (use a pencil as pencil is insoluble and won’t dissolve)
- Add a spot of ink to the line and place the sheet in a beaker of solvent (eg water or ethanol)
- Make sure the ink isn’t touching the solvent (as it will dissolve into it)
- Solvent seeps up the paper, carrying the ink with it
- Each different dye will move up the paper at a different rate and dyes will separate out
- If any dyes are insoluble it will stay at the baseline
- When solvent has reached top of paper, take paper out of beaker and leave to dry
What does filtration separate
Insoluble solids from liquids
How do you do filtration
- Pour the mixture into a filter funnel lined with filter paper with a beaker underneath
- The solid with get left behind in the filter paper while the liquid passes through
What are two ways you can separate soluble solids from solutions
Evaporation and Crystallisation