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
How do isotopes tend to be?
Unstable due to imbalance of protons and neutrons
More unlikely to decay
What is relative mass’s use and units?
- way of comparing particles
- measured in atomic mass unit (amu)
What is the fundamental charge used for?
equal to the size of the charge on a proton and an electron
What is the charge of proton, neutron, electrons?
Proton = +1
Neutrons = 0
Electrons = -1
What is the relative mass of proton, electrons, neutrons?
Protons = 1
Electrons = 1
Neutrons = 1/1840
How is nuclear charge atom stated as?
Relative charge of nucleus
What determines the relative
Proton number since nuclei is made
Define nuclear fission.
The splitting of a large, unstable nucleus into two smaller nuclei
What happens during fission?
A neutron collides with an unstable nucleus, the nucleus splits into two smaller nuclei
It also emits gamma rays
What happens to the products of fission?
- move away very quickly
- energy transferred is from nuclear potential energy to kinetic energy.
What happens to the mass of products during fission?
Mass of products is less than mass of nucleus
The remaining mass is converted into energy which is released during fission.
