Atomic structure -1

Question 1

What did Robert Boyle do and when did he do it

Answer 1

He proposed that there were some substances that could not be made simpler. These are the chemical elements we know. He proposed this in 1661.

Question 2

What did John dalton do and when

Answer 2

In 1803 he suggested that elements were composed of invisible atoms. All the atoms of a particular element had the same mass and atoms of different elements had different masses and atoms could not be broken down.

Question 3

What did Henri becquerel do and when

Answer 3

In 1896 he discovered radioactivity which showed that particles could come from inside the atom which meant that the atom was not indivisible

Question 4

What and when did JJ Thomson do

Answer 4

In 1897 he discovered the electron which was the first sub-atomic particle which was discovered. He showed that electrons were negatively charged and electrons from all elements were the same.

Also he suggested that electrons were located within the atom in circular rays, this is because electrons had a negative charge there had to be a source of positive charge inside the atom and because electrons are much lighter than whole atoms there had to be something to account for the rest of the mass of the atom.

Question 5

What did Ernest Rutherford do and when

Answer 5

In 1911 him and his team found that most of the mass and all the positive charge of the atom was in tiny central nucleus.

Question 6

What instrument can be used to take a photograph of an atom

Answer 6

Atoms can only be seen indirectly. A scanning tunnelling electron microscope

Question 7

What are protons and neutrons some times called

Answer 7

Nucleons

Question 8

What is the relative mass of a proton

Answer 8

1

Question 9

What is the relative mass of a neutron

Answer 9

1

Question 10

What is the relative mass of an electron

Answer 10

1840

Question 11

What is the relative charge of a proton

Answer 11

+1

Question 12

What is the relative charge of a neutron

Answer 12

0

Question 13

What is the relative charge of an electron

Answer 13

-1

Question 14

How are protons and neutrons held together

Answer 14

Strong nuclear force

Question 15

What holds electrons and protons together and where and how long does it happen

Answer 15

Electrostatic forces and it happens within the nucleus over very short distances

Question 16

What is stronger electrostatic force or strong nuclear force and what does this mean

Answer 16

Strong nuclear force which means that it overcomes repulsion in the protons in the nucleus.

Question 17

Why do we assume that there are the same number of protons and electrons in an atom

Answer 17

Because they have opposite charges of the same size and the atom is neutral

Question 18

Who were the main alchemists that developed the ideas of the atom

Answer 18

Robert Boyle 
John dalton 
Henri becquerel 
JJ. Thomson 
Ernest Rutherford

Question 19

The number of electrons is equal to the number of protons so what does this mean for the whole atom

Answer 19

The atom is electrically neutral

Question 20

What determines the chemical properties of an element and what sort of element it is

Answer 20

The number of electrons in the outer shell

Question 21

What does the atomic number define

Answer 21

The chemical identity of an element

Question 22

Calculating mass number

Answer 22

Protons + neutrons

Question 23

What is responsible for almost all the mass of an atom

Answer 23

Protons and neutrons because electrons weigh virtually nothing

Question 24

What is an isotope

Answer 24

Same proton number different number of neutrons

React chemically in the same way

Question 25

What is half life

Answer 25

Time taken for half for a radioactive isotopes radioactivity to decay

Question 26

What is the cause of radioactivity

Answer 26

Isotopes are unstable and so its nucleus breaks down giving of bits of nucleus or energetic rays