Splitting the Atom Flashcards
What are atoms made of?
Protons, Neutrons and Electrons
What is inside the nucleus?
Protons and neutrons.
What is the mass number in the periodic table?
The sum of the protons and neutrons in the nucleus
What is the atomic number in the periodic table?
The number of electrons and protons in an atom.
Where are electrons found?
Orbiting the nucleus
What are the charges of the particles in an atom?
Protons are positive, neutrons are neutral and electrons are negative.
What charge is the nucleus?
Positive
What are the characteristics of a nucleus?
It is very small and dnese and contains protons and neutrons.
What are the regions containing electrons called?
Electron shells or clouds
How many electrons can the first shell hold?
2
How many electrons can the second shell hold?
8
How many shells can the third shell hold?
16
How do you calculate the number of neutrons of an atom?
Subtract the atomic number from the mass number.
Eg. Iron has a mass number of 56 and an atomic number of 26. 56-26=30 neutrons. Since each atom is neutral, the number of negative electrons=the number of positive protons=26 for Iron
How is the periodic table organised?
Horizontal rows called PERIOD and vertical rows called GROUPS
How many groups are there in the periodic table?
8 groups
What characterises each group?
Each group behaves the same way
How do group 1, 2, 7 and 8 behave?
(a) group 1-alkali metals (all react strongly with water) (b) group 2-alkaline earth metals
(c) group 7-halogens (all brightly coloured)
(d) group 8-noble gasses (do not react with anything)
What happens when you move from left to right across each period of the periodic table?
The elements from from more metallic to less metallic from left to right.
What is on the left hand side of the periodic table?
Metals
What is on the right hand size of the periodic table?
Non-metals and metalloids (in between)
What is the relationship between groups and the electrons in their outer shell?
Elements in the same group have the same number of electrons in their outer shell (why they behave the same way)
E.g Group 1 elements all have one electron in their outer shell, group 2 elements all have two electrons in their outer shell etc.
What is the relationship between the period and the electron shells?
The period that an element belongs to corresponds to the number of shells for each atom.
e.g Lithium is in period 2 indicating it has two shells, one shell has 2 electrons and the other shell has 1 electron
What are the 4 trends of the periodic table?
- Atomic number and mass number: both increase across a period and down a group
- Atoms get bigger down a group and smaller across a period
- Metals become more reactive down a group
- Across a period metals become less reactive.
What is the aim of each atom?
Each atom tries to get 8 electrons in its outer shell. This is why the noble gasses (group 8) do not react at all
What is a molecule?
A combination of two or more elements
What is a molecule of an element?
Molecules composed of the same elements
e.g H2 Hydrogen O2 Oxygen
What is a molecule of a compound?
Molecules composed of different elements
e.g NaCl Sodium Chloride
What is the law of conservation of matter?
Matter can neither be created nor destroyed, but merely changed from one form or another.
This means that elements can combine to form compounds, that compounds can be decomposed into elements and that compounds can combine together to form different compounds, but the total amount of each element on earth cannot be changed.
What is the precipitation reaction?
Mixing 2 soluble liquids results in the formation of an insoluble solid called precipitate.
This happens because of ionic attraction of dissolved ions in the liquid
What is the decomposition reaction?
When a compound breaks down into 2 or more compounds through heat or electrolysis (using electrical current)
e.g h20 > H2 + 02
What happens in radioactivity?
Certain elements give off radiation when they decay or break down. This is as they have unstable nuclei which will break down to a more stable one releasing particles and energy from the nucleus.
What three kinds of radiation are there in radioactivity?
Alpha particle, beta particle and gamma rays.
What happens in nuclear fissions?
Nuclear energy is released when changes are made to the nuclei of atoms.
Nuclear fission is splitting heavy atoms into light atoms. When this happens a large amount of
energy is released.
How are nuclear fissions achieved?
By hitting the nucleus of an unstable neutron with an unstable atom.
How is nuclear energy positively used?
Mostly in electricity production, medicine, industry, agriculture, and environment.
How is nuclear energy harmful?
Weapons, radiation (causes changes to DNA/cancer, stays in environment for long time, nuclear waste (takes a long time to decay)
What are the advantages of using nuclear energy in electricity production?
Does not involve the emission of smoke and carbon dioxide or other pollutants while in use (does not contribute to greenhouse effect)
Produces huge amounts of energy from small amounts of fuel, small amount of waste, and is reliable.
What are the disadvantages of using nuclear energy?
Creates radioactive waste which is extremely toxic and harmful to both humans and the environment - needs to be stored safely underground, away from earthquakes, flooding, terrorists
Alot of money is spent on safety, and building nuclear reactors.
The explosion of nuclear weapons such as hydrogen and atomic bombs can lead to massive losses in terms of living and non-living things including the environment
Radioactive substances take an extremely long time to be completely decay.
