This element is mainly found in its red and white allotropes. For 10 points each:
[10e] Name this element with symbol P. Its white allotrope is used in matches due to its extreme flammability and reactivity, while its red allotrope is used as a flame retardant.
ANSWER: phosphorus
[10m] The most stable allotrope of phosphorus, its black allotrope, has very similar properties to this allotrope of a different element. This allotrope consists of hexagonal layers that can be peeled away individually with tape.
ANSWER: graphite
[10h] A phosphonium ylide is used to convert ketones and aldehydes into alkenes in this reaction. The Horner-Wadsworth-Emmons modification to this reaction replaces the ylide with a phosphonate ester.
ANSWER: Wittig reaction
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