Atomic Structure and the Periodic Table (1+2)

Question 1

What was

John Dalton’s model of the atom?

and when was this?

Answer 1

atoms are solid spheres (different spheres made up the different elements)

at the start of the 19th century

Question 2

What was

Rutherford’s model of the atom?

and when was this?

Answer 2

the nuclear model - most of the atom is empty space, there is a tiny, positively charge nucleus at the centre (where most of the mass in concentrated), a ‘cloud’ of negative electrons surrounds this nucleus

1909

Question 3

When were

protons disovered?

and by who?

Answer 3

1917

by Rutherford

Question 4

What was

Bohr’s model of the atom?

and when was this?

Answer 4

the nuclear model (improved) - electrons can only orbit the nucleus in fixed shells and aren’t found anywhere in between, each shell has a fixed energy

1913

Question 5

When were

neutrons discovered?

and by who?

Answer 5

1932

by James Chadwick

Question 6

What is the

relative mass of an electron?

Answer 6

0.0005

Question 7

What is the

radius of an atom?

Answer 7

1x10^-10 m

Question 8

What is the

radius of a nucleus?

and what is this in comparison to the atom?

Answer 8

1x10^-14 m

about 1/10 000 of the size of the atom

Question 9

What is the

atomic number?

Answer 9

the number of protons in an atom

Question 10

What is the

mass number?

Answer 10

the number of protons and neutons in an atom

Question 11

What are

isotopes?

Answer 11

different forms of the same element

these have the same number of protons but a different number of neutrons

(so the same atomic number but a different mass number)

Question 12

What is the

relative atomic mass of an element?

Answer 12

the average mass of one atom of the element compared to 1/12 of the mass of one atom of carbon-12

Question 13

What is the formula for

relative atomic mass of an element?

based on the abundance of different isotopes

Answer 13

(isotope1 abundance x isotope1 mass number) + (isotope2 abundance x isotope2 mass number) …

/ 100

Question 14

How did

Dmitri Mendeleev arrange the elements into his version of the Periodic Table?

(4 steps) and in what year?

Answer 14

1. First he sorted the elements into groups, based on their properties.
2. He realised that if he put the elements in order of atomic mass, a pattern appeared - he could put elements with similar chemical properties in columns.
3. A few elements seemed to end up in the wrong columns so he switched the order of the elements to keep those with the same properties in the same columns.
4. To keep elements with similar properties together, he also had to leave some gaps.

in 1869

Question 15

What are the

rows called in the Periodic Table?

Answer 15

periods

Question 16

How are

metals and non-metals separated in the Periodic Table?

Answer 16

by a zig-zag line running from boron to astatine

(hydrogen is a non-metal)