What is the chemical composition and formula for pencil lead?

Answer 1

pencil lead is just carbon

Graphite or pencil lead is an allotrope of carbon meaning that the atoms exist in different sturctural arrangements. See related links for structure of graphite

Answer 2

The core in pencils is made of graphite. It is a form of carbon where each atom is connected to three others via sp2 covalent bonds to form 'graphene' sheets; these sheets are then connected together by weak bonds (van der Walls forces) and have and interlaminar shear strength of only 34 MPa. Its formula is simply C(s), meaning that it is just elemental carbon in the solid state.

Staedtler Product Information: (composition varies by manufacture)

Pencil Number, Graphite %-wt, Clay %-wt, Wax %-wt

9H 41% 53% 5%

8H 44% 50% 5%

7H 47% 47% 5%

6H 50% 45% 5%

5H 52% 42% 5%

4H 55% 39% 5%

3H 58% 36% 5%

2H 60% 34% 5%

H 63% 31% 5%

F 66% 28% 5%

HB 68% 26% 5%

B 71% 23% 5%

2B 74% 20% 5%

3B 76% 18% 5%

4B 79% 15% 5%

5B 82% 12% 5%

6B 84% 10% 5%

7B 87% 07% 5%

8B 90% 04% 5%

Answer 3

The pencil is a writing instrument, not a substance.