"A nonpolar covalent bond forms when electrons are shared equally between atoms. A polar covalent bond forms when electrons are not shared equally…the more electronegative atom 'gets' more electrons than he gives away by sharing. A coordinate covalent bond is imagined to form when one atom donates the entire pair of electrons which are shared with the other atom.
A restaurant analogy for these situations could be as follows:
- A nonpolar covalent bond is formed if you give your friend half of your cheeseburger in exchange for half of his chicken burger.
- A polar covalent bond would be like your friend taking all of your cheeseburger and in exchange giving you just a small bite of his chicken burger.
- A coordinate covalent bond forms if you notice a homeless person outside, bring them into the restaurant, and give them your whole dinner to eat."
Source: Murray Hart, retired science teacher, previously posted at scienceanalogies.com
Read examples of scientific analogies
Here an atom is personified (referred to as a 'he') and an anthropomorphic metaphor is used ('he gives away').
Read about personification in science texts
Read examples of personifying nature
Read other examples of personification
The 'sharing' metaphor is widely used by chemists and in texts, so learners may come to think that a covalent bond binds atoms together because they 'share' electrons. Read about the ownership of electrons alternative conception.
