Topics 1,2 And 3 Flashcards
What are the electrons in an atom?
- move around the nucleus
- negative charge
- tiny
- no mass
- occupy shells
What is the charge on electrons?
The same as proton charge but opposite (negative)!
How many protons and electrons in an atom?
Equal amount
What are the characteristics of protons?
Heavy
Positively charged
What are the characteristics of neutrons?
Heavy
Neutral
What are the characteristics of electrons?
Tiny
Negatively charged
What is covalent bonding?
Sharing electrons - forming a molecule
Give two elements that were discovered by spectroscopy
Rubidium
Caesium
What test could you use to distinguish between a solution of sodium chloride and magnesium sulfate
Chloride - add dilute nitric acid and silver nitrate - will give a white precipitate of silver chloride
Sulfate - add dilute HCL and barium chloride solution - gives a white precipitate of barium sulfate
What colour would a flame be if A) sodium B) potassium C) calcium were out into it?
A) yellow orange
B) lilac
C) brick red
Explain why barium sulfate can be drunk even though it’s toxic
It’s insoluble
Opaque to X-rays
When drunk it shows up the gut so that any problems e.g blockages can be seen
A forensic scientist carries out a flame test to identify a metal. The metal burns with a blue - green flame. Which metal does this indicate?
Copper
Name two insoluble metal chlorides
Barium sulfate
Calcium carbonate
Describe how you would prepare a pure, dry sample of the insoluble salt barium sulfate
Mix solutions of barium nitrate and potassium sulfate
Filter out the precipitate of barium sulfate
Wash it with distilled water
Dry on filter paper
What is the chemical formula for A) potassium fluoride B) aluminium chloride C) sodium hydroxide
A) k+F-
B) Al+ Cl-
C) Na+ OH-
Explain the difference between a compound whose name ends in ‘-ate’ and who’s name ends in ‘-ide’
When two different elements combine the components name is something ‘-ide’
When three or more different elements combine and one is oxygen it’s often something ‘-ate’
List the main properties of ionic compounds
Regular lattice structure
High melting and boiling point
They conduct electricity when aqueous or molten
Are cations positive or negative ions
Positive
Describe the process of ionic bonding
- The Transfer of electrons. Atoms lose or gain electrons to form positively or negatively charged atoms called ions
- Shell with one electron will want to get rid of it to have a full outer shell
- A nearly full she wants the extra electron to have a full outer shell
- Groups 1/2 and 6/7 are likely to form ions
What are the groups in the periodic table? Explain the significance in terms of electrons
- Alkali metals, transition metals, halogens, noble gasses.
- elements in the same group have similar number of electrons in their outer shell
- group number equal to the amount of electrons in the outer shell
Explain how Mendeleev arranged known elements in a table. How did he predict new elements?
- 50 know elements according to their properties
- similar chemicals in the Same vertical groups - left gaps to make this work
- the gaps predicted the properties of undiscovered elements
What feature of atoms determines the order of the modern periodic table?
- metals and non metals opposite sides
- order of increasing atomic number of electron shells
- the properties of the elements change as you go along the period
The element boron has 5 protons how many electrons does it have in its outer shell?
5
Name the 3 types of particle in an oxygen atom
Proton
Neutron
Electron
Is it number of protons or the number of neutrons that defines each element?
Protons
Describe how you would work out the electron configuration of an atom, given its atomic number
What is the electron configuration of potassium
- The same number of protons and electrons
- 1st shell has 2 from then on each shell has 8 electrons
- potassium is 2:8:8:1
What does the atomic number and the mass number represent?
Mass: total number of protons and neutrons in the atom
Atomic: number of protons in the atom (same number of electrons)
Define the term isotope
Different atomic forms of the same element, which have the same number of protons but different number of neutrons
What is the nucleus in an atom?
- the middle
- contains protons and neutrons
- positive charge
- tiny
Kerosene and water are immiscible. Describe how you could separate a mixture of these two liquids
Shake together then allow to stand - they will separate into layers
Denser sinks to the bottom
Then separate using a separating funnel with a tap
What covalent bonds do simple molecular substances have?
Very strong covalent bonds to form small molecules of two or more atoms
Are simple molecular covalent substances strong or weak?
By contrast to the forces between they are very weak
Does simple molecular covalent substances have a high or low melting point and why?
Very low because molecules are easily parted from each other
What substances are simple molecular?
Liquids
Gas
Do molecular substances conduct electricity and why
No
There are no ions
What are giant molecular covalent substances?
Similar to lattices except there are no charged ions
What bond do giant molecular substances have?
Strong covalent bonds
Are giant molecular substances A) conductors of electicity and B) soluble in water?
A) not conductors of electricity
B) INSOLUBLE in water
What boiling point to giant molecular substances have?
Very high
Give two example of giant molecular substances
Diamond
Graphite
How many covalent bonds does diamond have?
4
Explain why it is possible to separate air by fractional distillation
Liquid air produces a variety of products e.g nitrogen and oxygen
How do you separate out miscible liquids?
Fractional distillation
How do you fractionally distil air?
- filter to remove dust
- cool to -200 degrees becomes miscible mixture of liquids
- during cooling water vapour condenses and is removed
- the liquified air enters the fractioning column and heated slowly
- the remaining gas is separated by fractional distillation
- oxygen n argon are. It separated so another column is used to separate them
Describe how paper chromatography could be used to analyse colouring agents in food
Run samples of known mixtures alongside unknown mixture and compare where the spots end up
What is the R(f) value of a chemical that moves 4.5cm when the solvent moves 12cm?
0.375 because R(f) = distance travelled by substance divided by distance travelled by solvent
