Intro to Chemistry
What is the 4-element theory?
In ancient Greece, philosophers believed all matter was made of 4 elements: fire, air, earth, and water.
What are the 3 subatomic particles?
Electrons, protons, and neutrons
What are the circles called that surround a nucleus?
Orbitals or shells
What is an isotope?
Atoms that have the same number of protons but different number of neutrons.
What is the atomic number for potassium?
19
Who first coined the term "atomos" AND what does it mean?
Democritus, who lived in 460 BC.
"Atomos" means "uncuttable" or "indivisible."
What charge do protons have AND what is their mass?
Charge: +1
Mass: 1 amu
What is an element?
A substance that is made of only one type of atom!
What did Dmitri Mendeleev contribute to the world of chemistry?
How many electron orbitals would you need for an atom that has 17 electrons?
3
(2 in the first shell, 8 in the second shell, 7 in the third shell)
What is chemistry?
The study of matter and the changes matter undergoes.
What charge do electrons have AND what is their mass?
What is the octet rule?
Atoms are most satisfied when they have 8 electrons in their valence shell.
If an atom has 3 protons, 7 neutrons, and 4 electrons, what is its net charge?
-1
The atomic mass shown on the Periodic Table represents a weighted average of all the isotopes of that element in nature. Since most atoms of carbon have a mass of 12, the average shown on the PT is very near to 12.
Who discovered the electron and how?
JJ Thomson. He shot a stream of particles between 2 metal plates, and saw the stream curve upward towards the positively-charged plate.
It curved more than it should have, based on the weight of an atom. Thus, this stream of particles must be negatively charged, and must weigh less than an atom.
He came up with the "plum pudding model."
What is in the nucleus of an atom?
Protons and neutrons!
What is the atomic number?
The number of protons in a certain "flavor" of atom.
What is radioactive dating?
A way to estimate the age of an object based on how much Carbon-14 it contains.
What keeps the protons in an atom from repelling each other?
The strong nuclear force!
What did Ernest Rutherford contribute to the chemistry world?
BONUS 100 points if you can give the year!
1911. Ernest Rutherford discovered the proton.
He performed the gold foil experiment, showing that positively-charged alpha particles at times bounce off gold atoms in random directions.
What is an "amu"?
Atomic mass unit. 1 amu = 0.000000000000000000000167 grams.
For atomic notation, what number goes in the top lefthand corner?
The atomic mass (protons and neutrons added)
How is the Periodic Table organized?
Horizontally: atoms increase in the number of protons
Vertically: elements are aligned with other elements with similar properties
What kind of atoms like to steal electrons? Give an example!
Those with 7 valence electrons! (Group 7 elements!)