Chemistry Topic 1- Atomic Structure and the Periodic Table

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What is the radius of an atom?
Around 0.1 Nanometres (1x10^-10 metres)
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Where is the nucleus and what does it contain?
It's in the middle of the atom- almost of the whole mass of an atomic is concentrated in the nucleus. It contains protons and neutrons
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What is the radius of the nucleus and what charge is it?
It has a radius of 1 x 10 ^ -14 metres and a positive charge because of the protons
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Describe electrons.
They move around the nucleus in electron and are negatively charged and tiny. The volume of their orbits determines the size of the atom
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Why are atoms neutral?
They have no overall charge because they have the same number of protons as electrons
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What does atomic number tell you?
How many protons there are
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What does the mass number tell you?
The total number of neutrons and protons in the atom
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What decides the type of atom?
How many protons they have
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What defines an element?
A substance that only contains atoms with the same number of protons
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What is an isotope?
Isotopes are different forms of the same element- they have the same number of protons but a different number of neutrons
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What is used instead of mass number when referring to an element as a whole?
Relative atomic mass, because elements can exist as a number of different isotopes
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What is the formula for relative atomic mass?
RAM= sum of (isotope abundance x isotope mass number) / sum of abundances of all the isostopes
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What is a compound?
Substances formed from two or more elements held together by chemical bonds. They usually require another chemical reaction to be separated.
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What is a mixture?
Elements and/or compounds mixed together with no chemical bond between them. They can be separated by physical methods.
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How John Dalton describe atoms?
He described them as solid spheres, and different spheres made up the different elements.
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How did JJ Thomson change this description?
He concluded that atoms weren't solid spheres, and discovered that an atom must contain even smaller, negatively charged particles- electrons. The new theory was known as the 'plum pudding model' -a ball of positive charge with electrons stuck in it
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What happened in 1909 during the alpha particle experiment?
Rutherford and Marsden fired positively charged alpha particles at an extremely thin sheet of gold. They were expecting the particles to pass straight through, but some were deflected more than expected and a small number were deflected backwards.
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What did this show?
There must be a tiny positively charged nucleus at the centre, where most of the mass is concentrated. A 'cloud' of negative electrons surrounds the nucleus, so most of the atom is empty space.
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What was the problem with Rutherford's theory and how was it amended?
Electrons in a cloud around the nucleus would be attracted to the nucleus, causing the atom to collapse. Neil Bohr's model of the atom suggested that all the electrons orbit the nucleus in fixed shells.
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How was the existence of protons and neutrons discovered?
Further experiments by Rutherford showed the nucleus can be divided into smaller particles which have the same charge as a hydrogen nucleus- these were called protons. James Chadwick provided evidence for neutral particles in the nucleus- neutrons.
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How was the periodic table arranged in the early 1800s?
It was arranged in order of atomic mass, and when this was done a periodic pattern was noticed. Early periodic tables were not complete and were placed in the wrong group because their properties were not considered
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How did Dmitri Mendeleev overcome this issue?
He put elements mainly in order of atomic mass but switched the order if properties didn't match up. Gaps were left the table to make sure that elements with similar properties stayed in the same groups- allowing Mendeleev to predict the properties.
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What are the properties of metals (metallic bonding)
strong (hard to break), but can be bent/hammered into different shapes (malleable), good conductors of heat and electricity, high boiling and melting points
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What are the properties of non-metals?
dull looking, more brittle, aren't always solids at room temperature, don't generally conduct electricity and have a lower density.
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Where are transition metals found in the periodic table and what is special about them?
They are in the centre of the periodic table and can have more than one ion (Copper can form Cu+ and Cu 2+). They are often coloured, and the compounds make good catalysts.
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Name the alkali metals.
Lithium, sodium, potassium, rubidium, caesium and francium.
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Why are they very reactive and have similar properties?
They all have one electron in their outer shell.
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What are the properties of alkali metals?
They are soft and have low density.
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What are the trends for the alkali metals as you go down group 1?
Increasing reactivity (outer electron more easily lost because it is further away from the nucleus), lower melting and boiling points, higher RAM
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What compounds do alkali metals form and what do they look like?
Alkali metals only ever form ionic compounds, which are generally white solid that dissolve in water to form colourless solutions
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What happens when the alkali metals react with water?
They react vigorously to produce hydrogen gas and metal hydroxides- salts that dissolve in water to produce alkaline solutions.
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Give an example of word equation for the reaction between an alkali metal and water
sodium + water ----> sodium hydroxide + hydrogen
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What happens when alkali metals react with chlorine?
They react vigorously when heated in chlorine gas to form white metal chloride salts
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Give an example of a word equation for the reaction between an alkali metal and chlorine.
sodium + chlorine ----> sodium chloride
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What happens when the alkali metals react with oxygen?
They react with oxygen to form a metal oxide- different types of oxide will form depending on the group one metal.
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Name the oxides produced by lithium, sodium and potassium.
Lithium= lithium oxide. Sodium= sodium oxide and sodium peroxide. Potassium= potassium peroxide and potassium superoxide
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Name the halogens and their coloured vapours.
Fluorine= very reactive, poisonous yellow gas. Chlorine= fairly reaction, poisonous dense green gas. Bromine= dense, poisonous red-brown volatile liquid. Iodine= dark grey crystalline solid or a purple vapour. They all exist as molecules (pairs)
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What are the trends as you go down group 7?
they become less reactive (harder to gain an extra electron because the outer shell is further away from the nucleus), higher melting and boiling points, higher RAM
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What happens when a halogen bonds with a metal?
They form 1- ions called halides.
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How does displacement occur with halogens?
More reactive halogens can displace the salt of a less reactive one.
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Name the noble gases.
helium, neon, argon, krypton, xenon, radon
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Why don't they react with other atoms?
They have a full outer shell, making them stable.
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Give three properties of noble gases.
They exist as monatomic gases (single atoms not bonded to each other), they are colourless gases at room temperature, they are non-flammable
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What are the trends as you go down group 0?
The boiling points and RAM increase. This is due to an increase in the number of electrons in each atom so they have greater intermolecular forces.
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Card 2

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Where is the nucleus and what does it contain?

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It's in the middle of the atom- almost of the whole mass of an atomic is concentrated in the nucleus. It contains protons and neutrons

Card 3

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What is the radius of the nucleus and what charge is it?

Back

Preview of the front of card 3

Card 4

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Describe electrons.

Back

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Card 5

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Why are atoms neutral?

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