3.1.1 Atomic structure Flashcards
What are the fundamental particles of an atom?
1.Protons
2.Neutrons
3.Electrons
What are the relative charges of each fundamental particle?
Proton= +1
Neutron= 0
Electron= -1
What is the relative mass of each fundamental particle?
Proton= 1
Neutron= 1
Electron= 1/1840
Describe the structure of an atom
A nucleus consisting of neutrons and protons, surrounded by electrons
What is the atomic (proton) number (Z)?
The number of protons in an atom
What is the mass (nucleon) number (A)?
The number of protons and neutrons (nucleons) in an atom
What is an isotope?
Atoms of the same element with the same number of protons but a different number of neutrons
Why do isotopes of the same element have the same chemical properties?
They all have the same number of electrons (which determines chemical properties)
Why do isotopes of the same element have different physical properties?
They have different numbers of neutrons (so their masses and densities are different)
What was John Dalton’s proposal of an atom?
- Elements were composed of indivisible atoms
- All atoms of a particular element had the same mass
- Atoms of different elements had different masses
- Atoms could not be broken down further (indivisible)
Who disproved that atoms were indivisible?
Henri Bacquerel (when he discovered radioactivity)
What did J J Thomson discover?
- The first subatomic particle - the electron
- That electrons were negatively charged and were common to all elements
What model did J J Thomson propose?
Theplum pudding model
* A sphere of a positive charge with an even distribution of electrons throughout the structure
What did Ernest Rutherford discover?
The nucleus of an atom
* Where most of the mass and all the positive charge of an atom is found
What force holds the nucleons of an atom together?
A strong nuclear force
* This force is much stronger than electronstatic forces
- This force only acts over very short distances (i.e: within the nucleus)
