- A pair of electrons shared between two atoms. Each of the positively charged nuclei is attracted to the same negatively charged pair of electrons.
- Covalent bonds are shown using 'dot and cross' diagrams.
- Covalent bonds between two hydrogen atoms are very strong.
- Whenever a bond is formed, energy is released which makes the atoms involved more stable.
- Covalent bonding causes each atom to have a full outer shell of electrons, therefore, noble gases cannot covalently bond.
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- One atom is more attracted to a pair of electrons more strongly than the other atom. The electron pair is pulled very close to that atom and away from the other.
- X loses control of its electron and becomes positively charged (a CATION). Y gains that electron and becomes negatively charged (an ANION).
- An ion is a charged particle.
- Ionic bonding is bonding in which there has been a transfer of eletrons from one atom to another to produce ions. The substance is held together by strong electrical attractions between positive and negative ions.
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- Most metals are hard and have high melting points, suggesting that the forces holding the particles together are very strong.
- The electrons are no longer attatched to atoms and flow around the whole metal; they are delocalised.
- Metallic bonding is an array of positive ions in a 'sea of electrons'.
- The strength of the bonds depends on how many electrons there are in the outer shell of the atom. The bigger the number, the stronger the bonds.
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