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Chemistry - Coggle Diagram
Chemistry
covalent bonding
a strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atom
this attraction is localised, only acting between the shared pair of electrons and the nuclei of the two atoms
a covalent bond is the overlap of atomic orbitals containing 1 electron to give a shared pair of electrons
example
boron forms 3 covalent bonds since it only has 3 outer electrons, meaning it will not form a full outer shell when covalently bonded (there will be 6 electrons)
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sulfur - can form 2,4 or 6 covalent bonds (can have up to 12 electrons in their outer shell)
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a double bond is an electrostatic attraction between two shared electron pairs and the nuclei of the bonded atoms
a triple bond is an electrostatic attraction between three shared pairs of electrons and the nuclei of the bonded atoms
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dative covalent bond
the electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms where both electrons have come from one atom
they are also known as a co-ordinate bond (represented by ->). The shared pair of electrons was originally a lone pair of electrons of one of the bonded atoms
Averge Bond Enthalpy
a measure of covalent bond strength. The larger the value, the stronger the bond (given in exams)
most covalent compounds have small molecules. They are gases, liquids (or solids) with low melting points and low boiling points
Instead of shellls, we now use energy levels
Each energy level is divided into subshells. The first energy level has the first subshells which holds 2 electrons
1S^2, 2S^2, 2p^6, 3S^2, 3p^2, 4S^2, 3d^10, 4p^6
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Example
K = 1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^1
Na + = 1s^2, 2s^2, 2p^6
since it is an ion, it loses one electron from 3s^1
the 4s subshell fills before the 3d subshell. For any d-block ion, the s-subshell empties first
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ionic bonding
the bonds between atoms always involve their outer electrons. Noble gases have full outer main levels of electrons and are very unreactive
when atoms bond together, they share or transfer electrons to achieve a more stable electron arrangement, OFTEN a full outer main level of electrons, likethe noble gases
an ion is a positively or negatively charged atom or group of atoms, where the number of electrons is different from the number of protons. When you lose or gain electrons, you form ions
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