Atoms and Electrical Charges

Atom

the smallest particle of an element that retains the characteristics of that element. -atoms are neutral

Electric Charge

-Can be positive or Negative -Like charges can repel or push away (ex: electrical charges build up in a brush and your hair, which causes your hair to fly away from the brush when you brush on a dry day) -Opposite or unlike charges can attract (ex: clothes in a dryer, they cling together) Positive charges repel Negative Charges repel Unlike charges attract

Dalton's Atomic Theory

1. All matter is made up of tiny particles 2.All atoms of a given element are similar to one another and different from atoms of other elements 3. Atoms of two or more different elements combine to form compounds. A particular compound is always made up of the same kinds of atoms and always has the same number of each kind of atom. 4. A chemical reaction involves the rearrangements, separation, or combination of atoms. Atoms are neither created nor destroyed during chemical reaction.

Electrons

A negatively charged subatomic particle having a minutes mass that is usually ignored in mass calculations -Symbol: e- -one electron has a mass of about 9.11 x 10^-28 g

Neutrons

A neutral subatomic particle having a mass of about 1 amu and found in the nucleus of an atom Symbol: n, N⁰, n⁰ The masses of the proton and neutrons in the nucleus determine the mass of an atom -about the same mass of proton -Protons and neutrons determine the mass of the nucleus Number of Neutrons in a nucleus = mass number - number of protons/atomic number

Subatomic Particles

A particle within an atom; protons, neutrons, electrons are subatomic particles (electric charges)

Proton

A positively charged subatomic particle having a mass of about 1 amu and found in the nucleus of an atom -Symbol: p or p+ -much heavier that electrons -one proton has a mass of 1.67 x 10^-24 g -Protons and neutrons determine the mass of the nucleus

Atomic Mass Unit (amu)

A small mass unit used to describe the mass of extremely small particles such as atoms and subatomic particles; 1 amu is equal to one-twelfth the mass of a carbon atom which has a nucleus containing 6 protons and 6 neutrons. -on the amu scale, the proton and neutron each have a mass of about 1 amu -electrons mass is too small to calculate the atomic mass

Atomic Number

Is equal to the number of protons in every atom of that element. -is the whole number that appears above the symbol of each element on the periodic table. -Atomic # = number of protons -can be used to identify the number of protons in an element -An atom is electrically neutral, thus the number of protons in an atom is equal to the number of electrons, which gives every atom an overall charge or ZERO. -Atomic # = number of electrons

Mass Number

The total number of protons and neutrons in its nucleus. -applies to a single atom only -Mass number = # of protons + # of neutrons ex: mass number 37 from an atom of Cl and atomic number of 17 = 20 neutrons