C1. Atomic Structure (Y10 - Autumn 1)

Question 1

🟠 What Is An Atom?

Answer 1

A atom is a single and pure element left on it’s own, which means in is not mixed in or chemically bonded with anything; it stays by itself. It is also the smallest part of an element that can exist.

Question 2

🟠 What Is A Molecule?

Answer 2

A molecule contains two or more atoms, whether it be of the same element or not and can be represented by formulae. (More than one atoms chemically joined)

Question 3

🟠 What Is An Element?

Answer 3

Elements are made up of atoms or molecules of which only contain one element throughout. There are over 100 known elements found in the periodic table.

Question 4

🟠 What Is A Compound?

Answer 4

A substance that contains two or more different elements chemically combined in fixed proportions. A compound can only be separated by back into elements by a chemical reactions.

Question 5

🟠 The Order of who found what in the Atom

Answer 5

(Oldest to Newest)

• (1800) Dalton
• (1897) JJ Thompson
• (1908-1913) Geiger, Marsden, Rutherford
• (1913) Bohr
• (1932) Chadwick

Question 6

🟠 What Was The Atom First Thought As? (Before Dalton)

Answer 6

For many years it was thought the smallest particle was the atom (from original idea by Democritus - a Greek philosopher).

Question 7

🟠 Dalton’s Evidience (1800’s)

Answer 7

Experimental evidence that support the existence of atoms which were to be thought of tiny spheres that could not be divided.

Question 8

🟠 JJ Thompson Evidence (1897)

Answer 8

He discovered the (negative) electron, along with the fact that atoms are made up of smaller particles.

He came up with the plum pudding model, which include a spherical cloud of positive charge, with electrons dotted around inside of it.

Question 9

🟠 Geiger, Marsden, Rutherford Evidence (1908-1913)

Answer 9

They decided to fire alpha particles (large positively charged particles) at a very thin gold foil.

The results were:

• Most of the alpha particles went straight through the gold atoms.
• Some of the alpha particles were deflected
• Some of the alpha particles bounced straight back

Question 10

🟠 Results/Observations and Conclusions of the Alpha Scattering Experiment

Answer 10

Results:

• Most of the alpha particles went straight through the gold atoms.
• Some of the alpha particles were deflected
• Some of the alpha particles bounced straight back

Conclusions:

• This concluded that atoms were mostly empty space to allow this to happen. As a result the atom was not as dense as first thought.
• This means that there were also some positive charge that was deflecting the positive atoms. This means there was some sort of positive located somewhere.
• This means that at the centre of the atom, there must be a great deal of mass, which turned out to be the central nucleus.

Question 11

🟠 Bohr Nuclear Model (1913)

Answer 11

He proposed that electron(s) orbit the nucleus in fixed shells or orbitals located at set distances from the nucleus.

Further investigation and experimentation revealed that the nucleus could be divided into smaller particles, each one having the same mass and charge.

Question 12

🟠 Chadwick’s Nuclear Model (1932)

Answer 12

Experimental work to provide the evidence to show the existence of neutral particles which were called neutrons (found in the nucleus).

Question 13

🟠 What are the Relative Masses and Charges of Protons, Neutrons and Electrons

Answer 13

(Sub-atomic Particle : Relative Mass | Relative Charge)

Proton : 1 | +1
Neutron : 1 | 0
Electron : Almost 0 (Negligible) | -1

Question 14

🟠 What is Relative Atomic Mass on the Periodic Table?

Answer 14

The number on the top of the symbol (AQA) and is the Protons + Neutrons in the particle

Question 15

🟠 What Is the Atomic (Proton) Number on the Periodic Table?

Answer 15

The number on the bottom of the symbol (AQA) and is the Protons in the particle

Question 16

🟠 Example Question: DESCRIBE why new evidence from the scattering experiment led to a change in the atomic model.

Answer 16

New evidence taken from the scattering experiment led to multiple changes in the atomic model. This was because before hand the plum pudding model was widely regarded as the main atomic model, however the fact that the alpha particles were partially deflected proved this theory wrong, and instead leans towards the idea of a central nucleus and orbiting electrons going round it.

Question 17

🟠 Example Question: DESCRIBE the difference between the ‘plum pudding’ model of the atom and the ‘nuclear’ model of the atom.

Answer 17

There are many differences the plum pudding and the nuclear model of the atom. The main one is the fact that there is a lot more empty space found in the nuclear model, whereas the plum pudding model contains a dense ball of positive charge with electrons scattered throughout. The nuclear model also includes neutrons and protons in a central nucleus, with the electrons orbiting it in fixed different shells instead.

Question 18

🟠 What are the scientific units for standard form numbers ranging from (x^-12 to x^12)

Answer 18

terra (T) x 10^12
giga (G) x 10^9
mega (M) x 10^6
kilo (k) x 10 ^3

milli (m) x 10^-3
micro (µ) x 10^-6
nano (n) x 10^-9
pico (p) x 10^-12

Question 19

🟠 What are Isotopes?

Answer 19

Isotopes are atoms of the same element that contain the same number of protons and electrons but a different number of neutrons.

Question 20

🟠 How to work out Relative Atomic Mass (Ar) of different Isotopes?

Answer 20

Ar = (% isotope A x mass isotope A) + (% isotope B x mass isotope B)
————————————-
100

Question 21

🟠 What is an Ion?

Answer 21

Ions are particles that contain a different number of protons and electrons and so they are electrically charged.

Question 22

🟠 Why are Ions formed?

Answer 22

Atoms often react to gain or lose electrons. When this happens they gain or lose electrons in order to get stable electron structure of a noble gas. (This means when their outer electron shell is full).