Structure and bonding in applications of science
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- Created on: 27-11-19 11:03
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- Structure and bonding in applications in science.
- The electronic structure of atoms.
- The nucleus contains the protons and neutrons. The electron orbit the nucleus in shells.
- Relative charge - Proton = +1 Neutron = 0 Electron = -1
- Relative mass - proton = 1 neutron = 1 electron = Very small (1/1840)
- Atoms are neutral (they have no overall charge)
- Therefore the number of protons = the number of electrons.
- Atomic number = number of protons in the nucleus of an atom. Mass number = protons + neutrons
- Number of protons = the atomic number of the atom.
- Number of electrons= same as the number of protons in the atom (not an ion).
- Number of neutrons = mass number - atomic number
- Group number = electrons in the outer shell Period number = number of shells
- Electronic structure and orbitals.
- A shell is also known as an energy level.
- Shells contain subshells which contain orbitals.
- An orbital is a region of space where an electron is likely to be found and each orbital holds 2 electrons.
- The size of the shell determines how many subshells it can contain.
- An s subshell has 1 orbital and can therefore hold 2 electrons. A p subshell has 3 orbitals and can therefore hold 6 electrons. A d subshell has 5 orbitals and can therefore hold 10 electrons.
- Shells contain subshells which contain orbitals.
- A shell is also known as an energy level.
- Bohr theory
- Electrons exist in fixed energy levels.
- An electron can exist in the 1st energy level or the 2nd energy level but it cannot exist somewhere in between.
- An electron can move to a higher energy level by absorbing radiation.
- An electron can fall to a lower level emitting radiation.
- An electron can move to a higher energy level by absorbing radiation.
- An electron can exist in the 1st energy level or the 2nd energy level but it cannot exist somewhere in between.
- Electrons exist in fixed energy levels.
- Ionic bonding
- Ionic bonding occurs between a metal and a non-metal.
- When the atoms react the metal atom loses electrons and the non-metal atom gains electrons. The atoms then become ions.
- An ion is something that has gained or lost an electron. Positive ions have lost electrons.
- The result of the electrostatic attraction between a positive and negative ion.
- Structure= a giant ionic lattice in which many ions are held together by strong electrostatic attractions.
- Ionic compounds have high melting and boiling points because of the giant lattice structures and there is a strong electrostatic attraction between the positive and negative ions.
- Ionic compounds don't conduct electricity when solid because ions cannot move.
- Ionic compounds conduct electricity when melted or in solution because the ions are free to move.
- The strength of the ionic bond is down to the attraction between the positive and negative ion. The bigger the attraction the greater the strength of the ionic bond.
- The more shells an ion has the bigger the ion will be.
- The size of the ion increases as you go down a group.
- The more protons in the nucleus the smaller the ion.
- The size of the ion decreases as there are more protons in the nucleus.
- Covalent bonding
- A covalent bond is formed between two non-metals.
- There is a strong electrostatic attraction between the two nuclei and the shared pair of electrons.
- Dative covalent
- Formed when both electrons in the shared electron pair come from one atom.
- Atoms that donate: group 5,6,7 Atoms that Accept: H+ and group 3.
- Single covalent bonds
- 1 electron pair is shared.Weakest and longest type of bond.
- Double covalent bond
- 2 electron pairs are shared.
- Triple covalent bond
- 3 electron pairs are shared. strongest and shortest type of bond.
- The electronic structure of atoms.
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