building units of matter.

 a fundamental substance made of one type of atom.

example: 4 elements common to all living things are oxyen, carbon, nitrogen, and hydrogen.

What is an atom?

the building units of elements. 

the smallest unit of an element;

It occupies space, has mass, and cannot be broken down into something else.

building blocks of atoms (or subatomic particles) are: protons, neutrons, and electrons.

carries a positive charge;

located at the nucleus, or core region of an atom.

represents the identity of the element.

atmoic number is the number of protons in an element.

carry no charge;

also located in the nucleus of atoms.

Adding the number of neutrons and protons in an atom, you can calculate the atomic mass.

carry a negative charge;

moves around the atoms nucleus and are in constant motion.

An atom will always have the same number of protons and electrons.

unique to each element;

the number of protons in the nucleus of an atom.

arranged the known elements in a repeating pattern, based on their chemical properties.

correctly predicted the existence of many elements that had not yet been discovered.

a radioactive isotope that spontaneously emits energy in the form of subatmoic particles and x-rays when its nucleus disintergrates.

This process is called radioactive decay (which can result in the transformation of one element into another).

molecules in which a radioisotope had been substituted for a more stable isotope. They can be delivered into a cell or multicelled body.

(used to discover specific reaction steps in photosynthesis and used in medicine)

a case of atoms sharing their electrons with one another.

attractive foreces between atoms/elements.

3 types of chemical bonds:

 ionic, covalent, and hydrogen.

molecules that consist of two or more different elements in proportions that never do vary.

i.e. water

two or more molecules intermingle without bonding.

i.e. sugar and water

an atom having an uneven number of protons and electrons; it carries a positive or negative electric charge.

cation - element with a positive charge

anion - element with a negative charge.

the close association of ions with opposite charges.

attractive forces formed from the exchanging of electrons.

produces ions.

when atoms share two electrons;

such bonds are stable and much stronger than ionic bonds.

two types:

Polar - two atoms do not share electrons equally. results in charge seperation (a north and south pole)

Nonpolar - two atoms sharing electrons equally. Between the same element.

most important chemical bond;

formed when hydrogen is bound to oxyen or nitrogen; 

a weak attraction that has formed between a covalently bound hydrogen atom and an electronegative atom in a different molecule or in a different region of the same molecule.

(they form and break easily)

ions and polar molecules easily dissolve in it.

something is showing a capacity to resist rupturing when it is stretched, or placed under tension.

water sticking together;

pH scales

 a way of measuring the concentration of hydrogen ions in solutions. The greater the Hydrogen concentration, the lower the pH. neutaility pH 7.0

ranges from 0-14

0-6 = acids

8-14 = bases

release hydrogen ions.