Chemical patterns Flashcards
What is constant about all the atoms of a specific element?
The number of protons (and therefore electrons unless ionised)
Who thought up the periodic table?
Mendeleev.
How is the periodic table organised?
Groups (vertical columns) and periods (horizontal rows)
Horizontal means?
This way ———————–
Vertical means?
Like a tree or a lamp post
How are the elements sorted in the periodic table?
Mendeleev used relative atomic masses, we use the proton number
All the elements in a group are?
Similar in their chemical reactions.
As you go down the periodic table the nuclei of the elements become?
Bigger and heavier
What did the fact not all elements had been discovered mean for Mendeleev’s periodic table?
There were gaps
Why were Dobreiner’s triads and Newlands’ octaves rejected?
Most elements did not fit their pattern.
How can data about physical properties in the periodic table be used?
To make predictions.
When elements are heated they produce…… flames?
coloured
What can the coloured light produced by heating an element be split into?
A spectrum that is unique to each element.
Name an element that was discovered using spectroscopy?
Helium, found on the sun before it was found on earth.
What is in the middle of an atom?
A small nucleus.
Where are the electrons in the atom?
Travelling around the outside in shells.
What is the charge on a proton?
+1
What is the mass of a proton?
1
What is the charge on a neutron?
0
What is the mass of a neutron?
1
What is the charge of an electron?
-1
What is the mass of an electron?
almost zero
Atoms must have the same number of?
Protons and electrons
How do you find the relative atomic mass?
Number of protons + number of electrons = relative atomic mass
How are electrons arranged in an atom?
In shells around the nucleus.
The shells have space for how many electrons (going out from the nucleus)?
2.8.8.18
What is the difference between electrons in different shells?
They have different energy levels.
Where would you find the electrons with the lowest energy?
Next to the nucleus
What do the elements in group 0 have that makes them inert?
Full electron shells.
What happens to the properties of the elements across a period? (Horizontal line)
There will be trends.
How many electrons are there in the outer shell of the metals?
Up to, and including, 3. Note - Hydrogen and Helium are not metals.
How many electrons are there in the outer shell of the non-metals?
5 or more.
If an element has the electron arrangement 2.8.1, what sort of element is it likely to be?
A metal
What is group 1 called?
The alkali metals.
What are group 1 metals like?
Soft, can be cut with a knife, shiny when first cut, tarnish quickly because they react with oxygen.
What happens to properties such as boiling point, melting point, density as you go down the group?
They show trends.
Metals form bonds by losing their outer electron. Which elements find it easier to lose electrons?
The ones where the nucleus is a long way from the electron, so the ones lower in the group.
What happens to the reactivity of alkali metals as you go down the periodic table?
It goes up.
What do group one metals do with water?
React - sodium fizzes and moves around, rubidium explodes. Hydrogen is produced.
How can you test for hydrogen?
It pops when lit.
What is left in solution when an alkali metal reacts with water?
Alkali metal hydroxide.
What colour would you expect an alkali metal hydroxide to turn an indicator?
Blue
The equation for the reaction of sodium with water is?
2Na(s) + 2H2O(l) => H2(g) + 2NaOH(aq)
How does sodium react with chlorine?
Vigorously, with a bright yellow flame. A white solid is left.
What is the white solid produced by the reaction of sodium with chlorine?
sodium chloride.
Give another name for sodium chloride.
Table salt.
Which elements are the halogens?
Group 7
What sort of molecules are the halogen elements?
Diatomic
The formulae of the halogens are:
Cl2; Br2, I2
Group 7 elements need to be used in a fume cupboard. Why?
They are corrosive and toxic.
How do group 7 halogens react with metal?
They form halides, eg chloride, bromide, iodide
Group 7 halogens need to gain an electron. Which halogens will find this easier?
The smaller halogens as the outer shell is closer to the nucleus
Where in the periodic table would you find the most reactive halogens?
At the top.
How many electrons in the outer shell of a halogen?
7
What is the reaction of metal + halogen?
Metal + halogen = > metal halide
What happens when a more reactive halogen takes the place of a less reactive halogen?
Displacement reaction.
Which is more reactive, chlorine or bromine?
chlorine
Can chlorine displace bromine in a potassium bromide solution?
Yes.
Can bromine displace chlorine in sodium chloride?
No, bromine is less reactive than chlorine and cannot displace it.
What are compounds of a group 1 element with a group 7 element like?
Solids with high melting points - ionic compounds in a crystal lattice.
What do ionic compounds do in water?
Dissolve
When are the ions free to move in an ionic compound?
In solution, or when melted.
When can an ionic compound conduct electricity?
When dissolved, or melted.
How do ionic compounds conduct electricity?
The ions move to the electrodes to complete the circuit.
How does a group 1 atom become an ion?
It loses an electron.
How does a group 7 atom become an ion?
It gains an electron.
Which electron does a group 1 element lose?
The one in the outer shell.
What charge ions do all group one metals become?
+1
Where does a halogen ion put the extra electron?
Into the outer shell.
What is the charge on a halogen ion?
-1
What is the charge on the OH ion?
-1
What is the charge on the sulfate (SO4) ion?
-2
What is the charge on the carbonate (CO3) ion?
-2
What is the charge on the nitrate ion? (NO3)
-1
