Structure of an atom Flashcards
Definition of a model
Simple way of showing or explaining a complicated object or idea based on evidence.
Definition of alpha particle
Particle with a positive charge given out by some radioactive elements - it is smaller than an atom.
Definition of electrons
Very small negatively charged particles in an atom.
Definition of neutrons
Particles with no charge in the nucleus of an atom.
Definition of protons
Positively charged particles in he nucleus of an atom.
Definition of a nucleus
The central part of an atom- contains protons and neutrons.
Definition of plum pudding model
Early model of an atom- a cloud of positive charge with electrons embedded in it.
Definition of shells
The paths or orbits that electrons move along in an atom.
Definition of Periodic Table
How the elements are arranged in order of their atomic number.
Name the scientist who showed that atoms contain negatively charged particles.
J.J. Thomson
What did J.J Thomson call his negatively charged particle?
Electrons
Why did J.J. Thomson assume that there also must be positively charged parts in an atom?
He assumed that there also must be positively charged parts in the atom because atoms are neutral- the opposite charges cancel each other out.
Why was J.J Thomson’s model called the plum pudding model?
His model was called as the plum pudding model because the electrons seemed to be spread out in a cloud of positive charge. The electrons were like the plums and the rest of the atom was the pudding.
Which particles were fired during the experiment carried out by Rutherford?
Small, fast moving alpha particles.
What is the charge of the particles that were fired on the gold sheet?
The charge of the particles that were fired on the gold sheet was positive.
What should be the observation, if the plum pudding model was correct?
If the plum pudding model was correct, the alpha particle should pass straight through the gold foil.
What were the actual observations of Rutherford after bombarding the particles?
The actual observations of Rutherford after bombarding the particles were that most of the particles went through, but a few were deflected- some even bounced back.
Describe the model of an atom suggested by Rutherford based on his evidence.
The model of an atom suggested by Rutherford based on his evidence was that the atom had a small, positively charged nucleus with the electrons arranged further away. He thought that the atom was mostly empty space.
Explain how Rutherford’s new model was similar to the plum pudding model.
Similarities that the Rutherford’s model had with the plum pudding model :
- They both had negative and positive charges.
- They both described an atom in sphere shape.
Explain how Rutherford’s new model was different from the plum pudding model.
Differences that the Rutherford’s model had with the plum pudding model were:
- In the plum pudding model there was no nucleus, where as, the Rutherford model had a nucleus.
- In the plum pudding model the electrons were embedded in a cloud of positive charge but in the Rutherford model there was a positively charges nucleus with electrons arranged further away.
What is present in the nucleus of an atom?
Protons and Neutrons
What is present in the shells of an atom?
Electrons
Write the charges of the following particles:
Protons-
Electrons-
Neutrons-
Protons- Positive
Electrons- Negative
Neutrons- Neutral
An atom does not have overall charges. Explain.
The atoms of an an element always have the same numbers of protons and electrons. This means that they have no overall charges- the opposite charges cancel each other out.
