Atoms And Isotopes Flashcards
Give an approximation for the radius of an atom?
1x10^-10 metres
What are the three subatomic constituents of an atom?
Proton
Neutron
Electron
Where is most of the mass of an atom concentrated?
Nucleus
Approximately what proportion of the total radius of an atom is the radius of the nucleus?
1/10,000
Describe the arrangement of protons, neutrons and electrons in an atom?
Protons and neutrons are found in the atoms nucleus
The electrons are found in discrete energy levels around the nucleus
What type of charge does the nucleus of an atom have? Why?
Positive charge
Nucleus contains protons and neutrons
Protons have positive charge
Neutrons have no charge
Give two ways that an atoms electron arrangement can be changed?
Absorbing em radiation
Emitting em radiation
Explain how an atoms electron arrangement changes when it absorbs em radiation?
Electrons move further away from the nucleus
They move to a higher energy level
Explain how an atoms electron arrangement changes when it emits em radiation?
Electrons move closer to nucleus
They move to a lower energy level
How does the ratio of electrons to protons in an atom result in the atom having no overall charge?
Number of protons and neutrons are equal
Protons and electrons have equal and opposite charges, so charges cancel out
What do all forms of the same element have in common?
All have the same number of protons
What is the name given to the number of protons in an atom?
Atomic number
What is an atoms mass number?
Total number of protons and neutrons in the atoms electron arrangement
What is an isotope of an atom?
An atom of an element that has a different number of neutrons but the same number of protons
How do atoms turn into positive ions?
Lose one or more of their outer electrons
Electrons are negatively charged so the resultant charge of the atom is positive
What may lead to a scientific model being changed or replaced?
The discovery of new experimental evidence which doesn’t agree with the existing theory
How did the plum pudding model describe the atom?
A ball of positive charge, with negatively charged electrons distributed evenly throughout it
Prior to the discovery of the electron what was believed about the atom?
Atom was believed to be invisible
Which experiment led to the plum pudding model being discarded?
Rutherford alpha scattering experiment
What is the name given to the currently accepted model of the atom?
The Bohr nuclear model
State the conclusions of the alpha- scattering experiment
Most of the mass of the atom is concentrated at the center in the nucleus
The nucleus is positively charged
What reinforces a scientific theory?
When experimental results agree with the hypothesised theoretical calculations and theories
What did James Chadwick’s experiments on the atom prove?
The existence of neutrons
