It would take a stack of about 50,000 aluminum atoms to equal the thickness of a sheet of aluminum foil from your kitchen

It would take a stack of about 50,000 aluminum atoms to equal the thickness of a sheet of aluminum foil from your kitchen

• 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

How many cuts were we able to make?

• 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.

mostly empty space

• mostly empty space

• small, positive nucleus

• contained protons and electrons scattered around the outside

electrons move in definite orbits around the nucleus

• electrons move in definite orbits around the nucleus

sometimes called the wave model

• sometimes called the wave model

• spherical cloud of varying density

• varying density shows where an electron is more or less likely to be

positively charged particles (+)

• positively charged particles (+)

• help make up the nucleus of the atom

• equal to the atomic number of the atom

• contribute to the atomic mass

• equal to the number of electrons

neutral particles; have no electric charge

• neutral particles; have no electric charge

• help make up the nucleus of the atom

• contribute to the atomic mass

negatively charged particles (-)

• negatively charged particles (-)

• found outside the nucleus of the atom in the electron orbits/levels

• each orbit/level can hold a maximum number of electrons

• 1st orbital = 2 electrons
• 2nd orbital = 8 electrons
• 3rd orbital = 8 electrons

move so rapidly around the nucleus that they create an electron cloud

• move so rapidly around the nucleus that they create an electron cloud

• mass is insignificant when compared to protons and neutrons

• equal to the number of protons

• involved in the formation of chemical bonds

found in the outermost energy level of the electron cloud (called the valence shell)

• found in the outermost energy level of the electron cloud (called the valence shell)

• involved in bonding

• determine the chemical properties of an element

atomic number = number of protons

• atomic number = number of protons

• in a neutral atom, the # of protons = the # of electrons

• atomic mass= the number of protons + the number of neutrons

the total number of protons and neutrons in an atom’s nucleus

• 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

Let’s use the Bohr Model to sketch a hydrogen atom.

• Let’s use the Bohr Model to sketch a hydrogen atom.

• notice the one electron in the first orbital

notice the two electrons in the first orbital/level and the six in the second

• notice the two electrons in the first orbital/level and the six in the second

notice the two electrons in the first orbital/level, eight in the second, and one in the third

• notice the two electrons in the first orbital/level, eight in the second, and one in the third

Using the whiteboard and the proton, neutron, and electron pieces, build the following atoms, and determine their atomic and mass numbers.

• Using the whiteboard and the proton, neutron, and electron pieces, build the following atoms, and determine their atomic and mass numbers.