The Atom

What is Matter? anything that has ________ and takes up ________ matter is made up of ________ What is Matter?

How Small are Atoms? (2 Volunteers) It would take a stack of about 50,000 aluminum atoms to equal the thickness of a sheet of aluminum foil from your kitchen If you could enlarge a penny until it was as wide as the US, each of its atoms would be only about 3 cm in diameter – about the size of a ping pong ball A human hair is about 1 million carbon atoms wide A typical human cell contains roughly 1 trillion atoms A speck of dust might contain 3x1012 (3 trillion) atoms It would take you around 500 years to count the number of atoms in a grain of salt

Activity: Rip or cut a standard piece of paper in half as many times as you can. Class Discussion: How many cuts were we able to make? ____ Do you think we could keep cutting the paper forever? Why or why not? You would have to cut the paper in half around thirty-one (31) times to get to the size of any atom.

What are Subatomic Particles? the smallest unit into which matter can be ____________________ ___________________________ of all matter comprised of a ________________(at it’s center) and an ___________________________ (surrounding the nucleus) made up of ___________ _particles smaller than an atom __________________ What is an Atom? What are Subatomic Particles?

Early Atom Models: What is the Rutherford Model? mostly empty small, positively (+) charged nucleus contained protons and electrons scattered around the outside Early Atom Models: What is the Rutherford Model?

Early Atom Models: What is the Bohr Model? electrons (-) move in definite ___________ around the nucleus Nucleus is made of ______________ (+) and ________________ (neutral).

Modern Atom Model: What is the The Electron Cloud Model? sometimes called the wave model spherical cloud of varying density varying density shows where an electron is more or less likely to be The Bohr Model is still used to help explain characteristics of the atom. Modern Atom Model: What is the The Electron Cloud Model?

+ What are Protons? ______________ charged particles (+) help make up the ___________ of the atom equal to the _________________ of the atom contribute to the _______________ equal to the ___________ of ________________ in a neutral atom. + - +

What are Neutrons? ____________particles; have no electric charge help make up the nucleus of the atom contribute to the _________ __________. + -

- What are Electrons? ______________ charged particles (-) found _____________ the nucleus of the atom in the electron _____________. each orbital/level can hold a maximum number of electrons 1st orbital = _________ 2nd orbital = _________ 3rd orbital = _________ + - -

What are Electrons? move so rapidly around the nucleus that they create an _____________________ mass is insignificant when compared to protons and neutrons equal to the _________ of _____________________ in a neutral atom involved in the formation of chemical bonds + - -

What are Valence Electrons? found in the outermost energy level of the electron cloud (called the ______________) involved in bonding determine the chemical properties of an element

How is the Atom’s Center Formed? Protons and neutrons are grouped together to form the “center” or ________________ of an atom Notice that the electrons are not a part of the nucleus - + - - -

Atomic Structure

How are Atoms Described? The Atomic Symbol: atomic number = ________________ in a _____________ atom, the # of protons = the # of electrons atomic mass= _________________ + _________________ How are Atoms Described? The Atomic Symbol:

What would be the atomic number of this atom? the number of protons in the nucleus of an atom What is Atomic Number? - + - - What would be the atomic number of this atom?

+ What is the Atomic Mass? + the total number of protons and neutrons in an atom’s nucleus expressed in Atomic Mass Units (amu) each proton or neutron has a mass of 1 amu What would be the atomic mass of this atom? - +  3  4 + - 3 protons + 4 neutrons = an atomic mass of 7 amu Why did we not account for the electrons when calculating the mass number? -

Hydrogen (H) Atom Let’s use the Bohr Model to sketch a hydrogen atom. notice the one electron in the first orbital P = Atomic # = E = P = N = Atomic Mass – Atomic # =

Oxygen (O) Atom notice the two electrons in the first orbital/level and the six in the second Bohr Diagram P = Atomic # ________ E = P N = Atomic Mass – Atomic #

Sodium (Na) Atom Bohr Diagram P = E = N = notice the two electrons in the first orbital/level, eight in the second, and one in the third Bohr Diagram P = E = N =