Chapter 22 - (The nuclear atom) Flashcards
What are atoms?
building blocks of all matters.
What is the size of matter?
radius of 1 x 10-10 m
What do atoms contain?
- dense nucleus at center
- electrons orbit around nucleus
- positively charges nuclei
- negatively charges electrons
What did Ernest Rutherford to investigate the Plum Pudding model?
- a beam of alpha particles (He 2+ ions) were directed at a thin gold foil
- expected the alpha particles to travel through gold foil and change direction, small amount.
What did Ernest discover from the Plum pudding experiment?
- most alpha particles passed straight through foil
- some alpha particles changed direction but continued through a foil
- a few aloha particles bounced back off the gold foil
What was observed when a-particles are fired at thin gold foil?
Most of them go through but a very small number bounce straight back
Why do majority A particles go straight through the thin gold foil?
Atom is mainly empty space
Why do some a - particles deflect through small angles?
Positive a - particles are repelled by positive nucleus which contains most of its mass.
Why is a very small number of a - particles deflected straight back?
Nucleus is extremely small.
Define ion.
An electrically charged atom or group of atoms formed by the loss or gain of electrons
How is a stable atom electrically neutral?
Same number of protons and electrons
How are positive and negative ions formed?
Positive ions - lose electrons ( more protons)
Negative ions - gain electrons (more electrons)
What is the structure made up of?
- positively charged nucleus at the center made up of protons and neutrons
- negatively charged electrons orbit around the nucleus
Why does the nucleus have a positive charge?
- Neutrons have no charge
- Protons have a positive charge
What does proton number determine?
The atomic number
What is the symbol for proton number?
Z
What is the symbol for nucleon numeber?
A
how is nucleon numbed or mama number determined?
Protons + neutrons
What is the symbol for Element?
X
What is a nuclide notation?
A group of atoms containing same number of protons and neutrons
What does the term nucleon mean?
A particle in the nucleus
What does the term nuclide mean?
a nucleus with a specific notation
Define isotopes.
Atoms of the same element that have an equal number of protons but a different number of neutrons
