Regents Biology

Ch. 6The Chemical Basis of Life

Atoms, Elements, &Molecules

Why are westudying

Chemistry?

Regents BiologyProton Neutron Electron

Hydrogen1 proton1 electron

Oxygen8 protons8 neutrons8 electrons

Everything is made of matter Matter is made of “ATOMS”

Atoms are the smallest unit

of matter

Regents Biology

Section 2.1 Atoms, Elements, and Molecules

Atomic Number – the number of protons located in the nucleus of an atom.

Atomic Mass – the number of protons and neutrons together. (also called the “Mass Number”)

Regents Biology

About 25 elements are essential for life Four elements make up 96% of living matter:

• carbon (C)

• hydrogen (H)

• oxygen (O)

• nitrogen (N)

Section 2.1 Atoms, Elements, and Molecules

Regents Biology

The World of Elements

C

Different kinds of atoms = elementsDifferent kinds of atoms = elements

H

ON

P SNa

K

Mg

Ca

Regents Biology

Molecules of Life Put C, H, O, N together in different ways to

build living organisms What are organisms made of?

carbohydrates sugars & starches

proteins fats (lipids) nucleic acids

DNA, RNA

Regents Biology

Elements come together to make compounds

Compound – A substance containing 2 or more elements.

Example Table Salt (aka – NaCl)

Elements Compounds

Section 2.1 Atoms, Ions, and Molecules

Regents Biology

Questions????