Unit 2: atoms, molecules, and ions

What are Dalton's atomic theories

• Atoms are indivisible and indestructible; they can be created/detroyed

• Atoms of a given element are identical in size, mass, and chemical properties
• Atoms make up elements

• All atoms are the same
• compounds are composed of more than 1 element

What is the plum pudding model?

Answer explanation

It is a circle with negative circles in the middle. Mostly empty space and pos. charge is spread over entire sphere.

The law of multiple proportions states that...

• The ratio of the masses of one element that combine with a fixed mass of another element can be expressed in small whole numbers
• The mass of an atom is always a multiple of the mass of a hydrogen atom
• The pressure of a gas is directly proportional to its temperature
• The volume of a gas is inversely proportional to its pressure

The ___ __ ____________ __ ____ states that atoms are not created nor destroyed in a chemical reaction

What was the order of discovery of subatomic particles and the people who discovered them?

• Proton by Rutherford, Electron by Thomson, Neutron by Chadwick
• Electron by Thomson, Proton by Rutherford, Neutron by Chadwick
• Neutron by Chadwick, Proton by Milikan, Electron by Thomson

• Electron by Thomson, Proton by MIlikan, Neutron by Rutherford

_________ discovered electrons using a _______. (add a comma between the two answers!!

Who measured the charge of an electron? Hint- used oil drop experiment.

• Albert Einstein
• Isaac Newton
• Robert Millikan
• Niels Bohr

what are Rutherford's experimental observations?

• Mass of p is 1810 mass of e-(1.67* 10^-27g)

• There is positive charge spread all over the nucleus

• Protons charge are the opposite of electrons.

• Atoms have a positive charge concentrated in the center

• Atoms are mosly empty space

Answer explanation

1840 not 1810

Label the following

• A- atomic mass

• A- mass number

• Z- Atomic symbol

• Z- atomic number

• X- symbol

How do you calculate atomic mass