Chemistry - Unit 2 Atomic Structure Test

isotope

isotope

atom/group atoms with the same atomic number (#of protons) but with different numbers of neutrons

ions

atom/ group of atoms w/ a + or - charge

cation

a positively charged ion

anion

a negatively charged ion

test your knowledge: an atom has 53 protons, 74 neutrons, and 54 electrons, what is the charge of this atom?

-1 charge

atomic mass

weighted average mass of atoms, protons + neutrons

percent abundance

percentage amount of all naturally occurring isotopes of an element

Fission

Splits an atom into 2 or more smaller ones

Describe Democritus' Atom

• The atom is the smallest

• There empty space between atoms

• Atoms have no internal structure, completely solid

What was Dalton's Atomic Theory?

Atoms of different elements have different size, mass, and properties.

What was JJ Thomson's Experiment?

Cathode Ray Experiment

• An electric charge was passed through an empty tube where all the air was sucked out

• The tube had a fluorescent screen placed in the back

• The screen allowed the electricity beam to be seen as a dot

• He then placed two oppositely charged electric coils inside the tube

• This resulted in the charge being deflected from the negative coil, and, because like charges repel each other, the charge also proved to be negatively charged

What did Thomson discover?

~ELECTRONS BABY~

What is Thomson's atomic model called? What does it look like?

Plum Pudding Model

• Sticky pudding: positively charged fluid that fills an atom

• Plums: negatively charged electrons that are suspended in the fluid

Thomson's model is okay, but what was wrong with it?

Atoms aren't filled with "positively charged fluid", and electrons aren't just floating around aimlessly like a bird

James Chadwick did stuff too ig. What subatomic particle did Chad discover?

neutrons ._.

Earnest Rutherford was earnest to find out more about these atom thingies. What was his experiment?

Gold Foil Experiment

• Alpha particles fired at a piece of gold foil

• Most of the alpha particles went straight through

What did Rutherford's Experiment prove?

Atoms are mostly empty space

What flaws are there with Rutherford's Experiment?

Rutherford created the planetary model, which is incorrect, because electrons don't have a set circular orbit around the nucleus

Who created the Quantum/ Electron Cloud Model

Erwin Schrodinger

What did the Quantum Model discover?

That electrons exist in "clouds" of probability

Name each subatomic particle, their location in the atom, mass, and charge.

• Protons, found in the nucleus, positively charged

• Neutrons, found in the nucleus, neutrally charged

• Electrons, circling around the nucleus, negatively charged

What makes each element unique?

The number of protons

Determine the average atomic mass of U-235 0.720% and U-238 99.28%

The average atomic mass of this is 237.9784

Determine the % abundancy for element X with two isotopes X-56 and X-58 with an avg atomic mass of 57.34 grams.

X-56 = 33 X-58 = 67

Why are ions formed?

Ions are formed because atoms want to become more stable, therefore, gain or lose electrons.

How many electrons in P -3 ion?

There are 18 electrons

What is the charge on lead (Pb) with 78 electrons?

It is +4

What electron configuration do most ions form?

Most ions form the electron configuration of a noble gas