Elements And Compounds

ChemistryDr. May

Atoms

An atom is the smallest part of an element that still has the properties of that element.

An atom is made up of protons, neutrons, and electrons

Atomic Inventory

Element Protons Neutrons Electrons

23

Na 11

35

Cl 17

11 12 11

17 18 17

Elements The 88 naturally occurring

elements are the “chemical alphabet” of all substances in the universe.

Elements can not be broken down by chemical or physical means to simpler substances.

Compounds And Elements

A tom s N a an d C l

Tw o o r m ore e lem en ts N a an d C l

M o lecu le N aC l

C om p ou n d Tab le S a lt

Elements And Atoms An atom is the smallest part of an

element that can enter into a chemical reaction.

22.98977 grams of sodium contains 6.02 x 1023 atoms of sodium

Compounds and Molecules The molecule is the smallest part

of a compound that still has the properties of that compound.

58.44 grams of NaCl (sodium chloride) contains 6.02 x 1023 molecules of NaCl

Elements in Galaxies 91.00% hydrogen

8.75% helium

0.25% others

Elements On Earth 49.2% oxygen (H2O, O2, CO2) 25.7% silicon (SiO2, silicates) 7.5% aluminum (Al2O3, minerals) 4.7% iron (Fe2O3, earth’s core) 3.4% calcium (CaCO3) 2.6% sodium (NaCl, Na2CO3) 2.4% potassium (KCl, K2CO3)

Earth Crust

Elements In The Earth’s Crust

Elements In The Human Body 65% Oxygen (H2O, protein) 18% carbon (RNA, DNA, protein) 10% hydrogen (H2O, protein, fat) 3% nitrogen (protein, DNA) 2% calcium (bones) 1% phosphorus (phosphate in

DNA)

Diatomic Elements Seven elements

occur as diatomic molecules.

Hydrogen (H2) Nitrogen (N2) Oxygen (O2)

Fluorine (F2) Chlorine (Cl2) Bromine (Br2) Iodine (I2)

The End This presentation was created for

the benefit of our students by the Science Department at Howard High School of Technology

Please send suggestions and comments to rmay@nccvt.k12.de.us