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science mid-chemistry test Flashcards

(64 cards)

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1
Q

What is the definition of an atom?

A

the smallest particle of an element

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2
Q

What is the definition of a molecule?

A

cluster of non-metal atoms bonded together

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3
Q

What is the definition of an element?

A

pure substance listed on periodic table, only has one type of atom

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4
Q

What is the definition of a compound?

A

a pure substance made from more than one type of element chemically bonded together

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5
Q

What is the definition of a mixture?

A

an impure substance made from different elements or compounds

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6
Q

How many elements werre known in the early 1800s?

A

around 30

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7
Q

Who developed the periodic table in 1817?

A

Johann Dobereiner

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8
Q

What did Johann Dobereiner do?

A

he spotted groups of elements with similar properties, he called these the law of triads

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9
Q

Who developed the periodic table in 1864?

A

John Newlands

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10
Q

What did John Newlands do?

A

he arranged the order in atomic mass and noticed that a pattern repeated after every 8 elements. Called law of octaves

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11
Q

What was wrong with the law of octaves?

A

it wasn’t widely accepted because the order went wrong after calcium

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12
Q

Who developed the periodic table in 1869?

A

Dmitir Mendeleev

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13
Q

What did Dmitri Mendeleev do?

A

ordered the elements in atomic mass but he realised there were elements that had not yet been discovered so he left gaps in between

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14
Q

How did Dmitri Mendeleev modify his table?

A

he swapped the order so elements with similar properties were put together because he thought they had been measured incorrectly. We know now he did this based off the atomic number rather than the mass

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15
Q

What are groups?

A

the columns

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16
Q

What are periods?

A

the horizontal rows

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17
Q

How are elements in a group linked?

A

they have similar properties to each other

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18
Q

Where are the metals and non-metals on the periodic table?

A

the metals are on the left, non-metals are on the right

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19
Q

Where are the transition metals on the periodic table?

A

in between groups 2 and 3

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20
Q

Why do elements become more metallic as you move from left to right?

A

they have an increase in electrons in the outer shell, become more likely to gain or share electrons when they form compounds

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21
Q

What do transition metals tend to form?

A

coloured compounds

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22
Q

What are the properties of noble gases?

A
  • non-metals
  • unreactive
  • colourless
  • exist as single atoms
  • have a full outer shell of electrons
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23
Q

What are group 1 elements called?

A

alkali metals

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24
Q

What are the properties of alkali metals?

A
  • very reactive

- must be stored in oil to keep away from air and water

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25
What are group 7 elements called?
halogens
26
What to halogens form when they react with metals?
salts
27
What are the properties of compounds?
- cannot vary the amount of each element - chemically joined together - properties different from the elements you started with - can only be separated again using chemical reactions
28
What are the symbols for sulfate, carbonate and nitrate?
``` SO4 = sulfate CO3 = carbonate NO3 = nitrate ```
29
What does filtration separate?
an insolube solid from a liquid
30
How do you filtrate?
mixture is passed through the filtration paper, residue stays on and filtrate passes through
31
What does simple distillation seperate?
a solvent from a solution
32
How do you use simple distillation?
liquid has a lower boiling than the solvent. Vapour passes through the cooling chamber and condenses to that it is ready to collect with a beaker
33
What does fracional distillation separate?
two or more miscible liquids with different boiling points
34
How do you use fractinoal distillation?
liquid with lowest boiling point is turned into vapour first and is colected into beaker. Next liquid comes through and can be collected with a different beaker
35
What is chromotgraphy used to separate?
dissolved substances
36
How does chromotography work?
some coloured substances dissolve in the solvent better than others so they travel further up the paper. Solution travels up the paper taking some of the coloured substances with it then the substances spread apart.
37
What is magnetism used to separate?
magnetic metals from non-magnetic substances
38
How does magnetism work?
separates the metal because it becomes attracted to it
39
What is crystallisation used to separate?
solution and solute
40
How does crystallisation work?
evaporate the solution to a smaller volume, allow to cool down and crystals are formed which can be obtained through filtration
41
What is a separating funnel used to separate?
two immiscible liquids
42
How does a separating funnel work?
allow layers to form and turn on the tap until all of the second layer has passed through
43
What is the radius of an atom?
0.1nm
44
How much of a nucleus is an atom?
1/10,000
45
How do you convert nanometres to metres?
multiply by 10^-9
46
How do you convert metres to nanometres?
divide by 10^-9
47
Who developed the atom in 400BC?
Democritus
48
How did Democritus develop the atom?
proposed everything we made out of particles called atoms. Hypotheissied they couldn't be changed in shape or size or temperature and theat there were an infinite amount and they werer invisible
49
Who devoloped the atom in 1803?
John Dalton
50
How did John Dalton develop the atom?
- thought atoms were like billiard balls - said all atoms of the same element are identical in terms of their mass and properties - chemical changes take place when atoms link up or sepearate from each other - atoms not added or destroyed when chemical changes happen
51
Who developed the atom in 1897?
J.J. Thompson
52
How did J.J Thompson develop the atom?
discovered the electron, proved the atom could be brokend own into smaller pieces. Developed the "plum pudding" model, negatively charged electrons embedded in a ball of positive charge
53
Who devloped the atom in 1911?
Rutherford and Marsden
54
How did Rutherford and Mardsed develop the atom?
fired a beam of alpha particles at a gold leaf. Most passed straight through but some changed direction and some bounced back. Plum pudding scrapped for nuclear model, Rutherford suggested that it had a dense nucleus and most of it was empty space
55
Who devloped the atom in 1913?
Niels Bohr
56
How did Neils Bohr develop the atom?
said that electrons orbited the nucleus at fixed distances and that a fixed amount of energy is needed to move from one orbit to another
57
Who devloped the atom in 1920?
Rutherford
58
How did Rutherford develop the atom?
when he shot one atom into another Hyderogen nuclei wer always given. Showed that Hydrogen played an important role in the atomic structure. Later scientist just began to refer it as proton
59
Who devloped the atom in 1932?
James Chatwick
60
How did James Chatwick develop the atom?
predicted tat there was another sub-atomic particle because if they were all protons then they would break because of the repulsive forces, later discovered the neutron
61
What are isotopes?
atoms of the same element with different numbers of neutrons, have the same atomic number but different mass numbers can either be radioactive or non-radioactive
62
What is relative atomic mass?
the average mass of atoms of an element taking into account the mass and amount of each isotope it contains on a scale
63
How do you work out relative atomic mass?
total mass of all atoms of that element / total number of atoms of that element
64
Three rules of electrons?
- electron fill shells from nucleus outwards - the shell must fill before you can start the next one - each shell will hold a specific number of electrons

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