Chapter 2 Flashcards
State some differences between a metal and non-metal.
. Metals are good conductors of electricity and heat, as they mostly have free electrons.
. They’re all solids at room temperature, except for mercury, and most of them having HIGH melting points.
. Most of them can be hammered into different shapes (they’re malleable) and drawn into wires (They’re ductile).
. Non metals are poor conductors of electricity and heat (not carbon).
. Have low melting points.
. When solids non metals are hammered, they break into pieces, meaning they’re brittle.
. What is known as ‘radioactivity’?
. How’d you describe the word ‘radiation’?
. How’s radiation detected?
. Radioactivity is the release of energy from the decay of the nucleus of certain kinds of isotopes and atoms. Whenever an atom decays, it gives out radiation from its nucleus.
. Radiation is the energy given off by a decaying nucleus as high speed rays or particles.
. Radiation is detected using a geiger counter.
. What’s known as ‘atomic number’ and ‘mass number’?
. What are the subatomic particles of an atom?
Atomic number is the number of protons and electrons in an atom, and the mass number is the sum of protons and neutrons.
. Protons, Neutrons and Electrons.
. Describe the arrangements of particles (electrons) in an atom.
. What is meant by ELECTRONIC CONFIGURATION?
. In an atom, there’re different levels for the electrons to travel, called electron shells. There’re usually 3 shells in an atom, first can hold 2 electrons, second one 8, and the third one can hold 8 too.
. Electronic configuration is the electron arrangement in an atom, according to the shells, for example, the E.C for sodium atom is (2,8,1) i.e. there’re two electrons on the 1st shell, 8 on the second, and 1 on the third shell.
What are known as ‘isotopes’? (2 facts)
. Isotopes are the atoms of the SAME element, with same number of protons and electrons, but with different numbers of NEUTRONS.
. An isotope of hydrogen with 1 neutron is called a deuterium, and with 2 neutrons is called tritium.
What does the period and the group number of an element tells us?
. The group number of an element tells us the maximum number of electrons the element has on the outermost shell.
. The period where an element is situated tells us the number of filled shells the element has.
State the special names of certain groups.
Group I - The Alkali metals
Group II - The alkaline earth metals
Group VII - The Halogens
Group O - Noble gases
What is known as ‘nuclear fission’ ?
Nuclear fission is the splitting of an atom or nucleus by the use of energy. In uranium atoms, they’re struck by a neutron and split into two, giving out gamma rays.
What’s known as atomic bomb?
Atomic bomb occurs when the chain reaction gets out of control, leading the bomb to explode, which gives out intense heat, and deadly burst of radiation.
Explain how the fission of uranium-235 can be used to produce electricity.
In the nuclear power plants, there’re reactors filled with uranium-235 and water.
Then the splitting of the uranium by the neutrons gives out energy which turns that water into steam, and that steam turns on the turbine, which drives a generator to generate electricity. To ensure that the chain reaction doesn’t become an atomic bomb, there are control rods (mostly made up of boron) which controls the reaction process and heat produced. To stop the reactor, the rods are pushed into the reactor, absorbing all the excess neutrons produced during the fission, which stops the chain reaction, respectively.
State the different types of radiation.
. Alpha particles - Made up of 2 protons and 2 neutrons. They shoot out of atoms at very high speed, but slows down in the air. Paper and Skin stop them.
. Beta particles - They’re fast electrons, which are produced by the breaking up of neutrons to give out protons and electrons. They can pass through your skin, unlike Alpha particles.
. Gamma rays - These are very high energy rays, travelling up to several meters of air. They can pass through deep inside your body.
Explain the ways in which radiation can be used in real life.
. Tracers - Oil is carried often in long buried pipes, in long distances by engineers. To check is the pipes have leaks, a radioactive substance is added to the oil. If there is a leak, the oil seeps into the ground, as gamma rays. And that radiation is then detected by a geiger counter. The radioactive substance here, is called TRACERS.
. Cancer treatment - Gamma rays are the most dangerous types of radiation, as they can pass deep into the body, killing cells and causing cancer. But a weak beam of them, such as Cobalt-60, can be used to kill cancer cells, for treatment.
. Carbon dating - When a living being dies, it takes in no more Carbon atoms. From time-to-time, the Carbon-14 atoms in it start to decay, giving out radiation, and gets fewer. Measuring the radiation from them the age of dead remains can be worked out.
This process is called CARBON DATING.
Give the special features that the groups of the periodic table has.
Group I - Alkali Metals (Li, Na and K)
. They 3 are all metals
. Light, they can float on water
. Have low m.pt and b.pt, unlike other metals.
Lithium is the least reactive, and Potassium the most of the three.
Group VII - Halogens (Chlorine, Bromine and Iodine)
. Are non-metals
. Chlorine is a green gas, bromine a red liquid, and iodine black solid.
. Are poisonous
Chlorine is the most reactive, and Iodine the least.
Group O - Noble gases (He, Ne, Ar)
. Are non-metals
. Are colourless and gases
The elements in the noble gases are completely unreactive, as their atoms have full outer-shell electrons.
When do elements react in a similar way?
Elements react in a similar way, if their atoms have the same number of outer-shell electrons.
