Chem Basics CHAP 4

Question 1

History: In the 4th Century BCE, Greek philosopher Democritus did what?

Answer 1

Democritus came up the the theory of atoms or the “invisible units that make up the universe” more than 2,000yrs ago

he had no concrete supportive evidence

Question 2

Atomos

Answer 2

Greek word meaning “unable to be cut or divided.”

Question 3

Law of Definite Proportions

Answer 3

A chemical compound ALWAYS contains the Same Elements in exactly the Same Proportions by weight or mass.

Example: Water is always 89% Oxygen and 11% Hydrogen

Question 4

History: In 1808, an English schoolteacher named John Dalton did what?

Answer 4

Proposed a revised atomic theory: ALL atoms of a given element are exactly alike, and atoms of different elements can join to form compounds.

he had supportive evidence, but wasn’t right about everything

Dalton’s Theory laid the groundwork for for modern atomic theory.

Question 5

Dalton’s Atomic Theory

Answer 5

ALL atoms of a given element are exactly alike, and atoms of different elements can join to form compounds.

Question 6

History: In 1897, a British scientist named J.J. Thomson discovered what?

Answer 6

There are negatively charged particles (electrons) in atoms.

He discovered this during a cathode-ray tube experiment.

Question 7

The Plum-Pudding Model

Answer 7

“Electrons are spread throughout the atom, like plums in a pudding!”
- J.J. Thomson, probably

(statement isn’t 100% accurate)

Question 8

Electron

Answer 8

subatomic particle with a negative charge - lives outside the nucleus

Question 9

Rutherford’s Model of the Atom

Answer 9

Ernest Rutherford, another British scientist like Thomson, proposed most of an atom’s mass is concentrated in its center

Aha! The NUCLEUS exists

Question 10

Nucleus

Answer 10

The dense core of an atom - its center

Question 11

What’s in a nucleus?

Answer 11

Protons and Neutrons

Question 12

Proton

Answer 12

a subatomic particle with a positive charge - found chilling in a nucleus

Question 13

Neutron

Answer 13

a subatomic particle with no charge - found chilling in a nucleus

Question 14

Who’s smaller? Proton, Neutron or Electron

Answer 14

Electrons are. By a lot.

Question 15

True or False: Elements can have a number of protons (aka an Atomic Number) that matches another elements’!

Answer 15

FALSE

Each element has a unique Atomic Number (Z)

Question 16

Ion

Answer 16

a charged atom

Question 17

What makes an atom charged?

Answer 17

gaining or losing Electrons

Question 18

True or False: Most unreacted atoms have an overall charge.

Answer 18

FALSE

Most atoms have an equal amount of protons (positive particles) and electrons (negative particles) that cancel each other out.

Question 19

What do you call a charged atom?

Answer 19

an Ion

Question 20

How does an atom become charged?

Answer 20

it loses or gains electrons

Question 21

Electric Force

Answer 21

Opposites Attract! Describes how Negative and Positive charges attract one another and hold on tight

Question 22

What is the glue that holds an atom together?

Answer 22

Electric Force!

you see, when a positive and negative charge love each other very much…

Question 23

Atomic Number (Z)

Answer 23

the # of Protons in an element

Question 24

Atomic Digit (N)

Answer 24

“what the fuck” IS the correct answer!

This doesn’t exist. Individual elements CAN have different numbers of neutrons.

Question 25

True or False: The number of Protons and Electrons in an atom match!

Answer 25

True

Question 26

Mass Number

Answer 26

Total # of Protons + Neurons in the nucleus

Question 27

Isotope

Answer 27

an atom with the same # of Protons but an ABN # of Neutrons (compared to other atoms of the same element)

Question 28

Do Isotopes of an element have the same mass as another atom of the same element?

Answer 28

The mass of isotopes can vary due to a different amount of neutrons being in the nucleus

Question 29

Radioisotopes

Answer 29

Unstable Isotopes they emit radiation and decay until the isotope reaches a stable form Decays at a fixed rate

Question 30

True or False: To the left of an abbreviated element, the Atomic Number is a subscript.

Answer 30

True! Mass # would be above it, if expressed at all

Question 31

unified atomic mass unit (u)

Answer 31

A unit of mass used that describes the mass of an atom or molecule (due to tininess) 1/12 of the mass of a Carbon-12 atom

Question 31

The average atomic mass of an element is based off average mass AND that of isotopes equally.

Answer 31

No. It's a weighed average (isotopes - the less common they are, the less they factor in)

Question 32

the atomic mass unit (amu)

Answer 32

1/12 the mass of a carbon-12 atom (1.0u) aka the unified atomic mass unit (u)

Question 33

Mole (mol)

Answer 33

SI base unit to measure amount of a SUBSTANCE whose # of particles = the # of carbon atoms in exactly 12g of carbon-12 It's an important number due to there being SO MANY particles out there

Question 34

1 mol = ?

Answer 34

6.022(10^23) - Scientific Notation also 602,213,670,000,000,000,000,000 particles

Question 35

Avogadro's Number

Answer 35

6.022(10^23) aka the # of particles in 1 mole (mol) aka the # of atoms in 12.00g of carbon-12 named after Amedeo Avogadro, an Italian scientist

Question 36

Molar Mass

Answer 36

the MASS of one Mole (in grams or g/mol) it generally equals the avg Atomic Mass of the element being measured

Question 37

True or False: You can pinpoint the exact coordinates of an electron.

Answer 37

False. They are too small, move WAY too fast, and don't have a set path.

Question 38

Electron location is _______ to ______ levels.

Answer 38

Limited; Energy Levels They can not move "Up" (out) or "Down" without energy gain or loss.

Question 39

True or False: Electrons can be found between levels.

Answer 39

False.