Bio - CHAP 1

anything that takes up space and has mass

A substance that cannot be broken down to other substances by chemical reactions

A substance consisting of two or more different elements combined in a fixed ratio

A compound has characteristics different from those of its elements

Carbon (c), Oxygen (O), Hydrogen (H), Nitrogen (N) make up 96%.

Phosphorus (P), Sulfur (S), Calcium (Ca), Potassium (K) and a few others make up the remaing 4%.

those requried by an organism in only minute quantities

smallest unit of matter that still retains the properties of an element

the even smaller parts of the atom which consists of the proton, electron and neutrons

electrically neutral subatomic particles

positively charged subatomic particles

Negitively charged subatomic particle

dense core

at the center of the atom

protons give the nucleus a postive charge with negitively charged electrons form a cloud around it

a unit of measurement used for atoms, subatomic particles, and molecules

the dalton is the same as the atomic mass unit (amu)

The number of protons in an atom

which is unique to that element

written as a subscript left of the symbol for the element ----->>(₂He)

this number tells us that the helium atom has 2 protons in the nucleus

Unless indicated otherwise, atoms are neutral in electrical charge and therefore has the same number of electrons

Sum of protons and neutrons in the nucleus of an atom

written as superscript to the left ----->>(₂⁴He)

you can determine the number of neutrons by subtracting the number of protons (atomic nubmer) from the mass number