Ch 2 - Atoms and Elements

Question 1

Law of Conservation of Mass

Answer 1

Antoine Lavoisier

In a chemical reaction matter is neither created or destroyed.

Question 2

Law of Definite Proportions

Answer 2

Joseph Proust

All samples of a given compound, regardless of their source or how they were prepared, have the same proportions of their constituent elements.

H20 is H20 everywhere in the world.

2:1 ratio

Question 3

Law of Multiple Proportions

Answer 3

John Dalton

When two elements (A and B) form two different compounds, the masses of element B that combine with 1g of element A can be expressed as a ratio of small whole numbers.

Question 4

Atomic Theory

Answer 4

John Dalton

1 - Each element is composed of tiny indestructible particles called atoms.
2 - All atoms of the same element have a given mass and other properties that distinguish them from the atoms of other elements.
3 - Atoms combine in simple, whole number ratios to form compounds.
4 - Atoms of one element cannot change into atoms of another. In a chemical reaction the atoms only change how they are bound together.

Question 5

Cathode Ray Experiment

Answer 5

J.J. Thomson’s experiment

Applied a high electrical voltage between two electrodes. Discovered electrically changes particles for the first time. Declared the “Plum Pudding” atomic model.

Question 6

Electrostatic Forces

Answer 6

fundamental property of some of the particles that compose an atom(Positive and Negative charges) that either attract or repulse forces.

Question 7

Electric Field

Answer 7

The area around a charged particle where electrostatic forces exist.

Question 8

Electron

Answer 8

J.J. Thomson

a negatively charged, low mass particle present within all atoms.

Question 9

Millikan’s Oil Drop Experiment

Answer 9

Let oil drop by gravity through an electrically charged gas towards a negatively changes metal plate. The oil drops fall would slow, stop, or reverse depending on the strength of the charge.

Question 10

Electron Charge

Answer 10

-1.60 X 10^-19 C(coulombs)

Fundamental charge of a single electron.

Question 11

Charge to Mass ratio

Answer 11

-1.76 X 10^8 coulombs(C) / gram(g)

Question 12

Radioactivity

Answer 12

Henri Becquerel and Marie Curie

The emission of small energetic particles from the core of certain unstable atoms.

Allowed researches to probe the structure of an atom.

Question 13

Types of Radioactivity

Answer 13

Alpha(+ and most massive), Beta, and Gamma

Question 14

Rutherfords Gold Foil Experiment

Answer 14

Ernest Rutherford.

Attempted to prove Thomsons “Plum Pudding” model but instead disproved it on accident.

Found alpha particles were deflected off of something in the middle of an electron cloud and therefore there was something holding electrons together at the center. Basis for the Nuclear Model(Nucleus in electron cloud contains Neutron and Protons)

Question 15

Nuclear Theory

Answer 15

Ernest Rutherford.

1. Most of the atoms mass and all of its positive charge are contained in a small core called the nucleus.
2. Most of the volume of the atom is empty space, throughout which tiny, negatively charged electrons are dispersed.
3. There are as many negatively charged electrons outside the nucleus as there are positively charged particles(protons) within the nucleus(atom is neutral)

Question 16

Nucleus

Answer 16

Small core of an atom with most of the atoms mass and all of the positive charge. Contains both neutrons and protons and accounts for over 99% of the atoms mass.

Question 17

Proton

Answer 17

positively charged particles within the nucleus

Question 18

Neutrons

Answer 18

Neutral particles within the nucleus

Question 19

Atomic Mass Unit(amu)

Answer 19

1/12 the mass of a carbon atom containing six protons and six neutrons.

1 Proton = 1 amu
1 Neutron = 1 amu
1 Electron = 0.00055amu

Question 20

Atomic Number(Z)

Answer 20

The number of protons in an atoms nucleus.

Question 21

Chemical Symbol

Answer 21

each element is defined by its unique atomic number and represented by a symbol.

Question 22

Isotopes

Answer 22

Atoms with the same number of protons but differing numbers of neutrons.

Question 23

Natural Abundance

Answer 23

The relative amount of each different isotope of an atom naturally occurring in a sample.

Question 24

Mass Number(A)

Answer 24

the sum of an atoms protons + neutrons(isotopes chance the number slightly)

Question 25

Ions

Answer 25

Atoms who has either lost of gained electrons giving them either a positive or negative charge.

Question 26

Cation

Answer 26

Positively charged Ions.

Question 27

Anion

Answer 27

Negatively charges Ions.

Question 28

Periodic Law

Answer 28

Dmitri Mendeleev.

When the elements are arranged in order of increasing mass(not atmoic number like today), certain sets of properties recur periodically.

First periodic table.

Question 29

Periodic Table

Answer 29

Classification of elements based on increasing atomic number and their properties.

Metals, nonmetals, and metalloids.

Question 30

Metals

Answer 30

lower left side and middle of periodic table.

Good conductors of heat and electricity, malleable(into flat sheets), ductile(drawn into wires), often shiny, tend to lose electrons when they undergo chemical change.

Chromium, copper, strontium lead, etc.

Question 31

Nonmetals

Answer 31

upper right corner of periodic table divided by a zig zag line towards bottom right from Boron to Astatine.

Varied properties. Generally poor conductors of heat and electricity and all tend to gain electrons when they undergo chemical change.

Oxygen, sulfur, carbon, bromine, iodine, etc.

Question 32

Metalloids

Answer 32

Mixed properties of metals and nonmetals.

Many are semiconductors. Good for anything with computer chips.

silicon, arsenic, antimony etc

Question 33

Semiconductor

Answer 33

Type of metalloid.

intermediate(highly temperature dependent) electrical conductivity. Very useful.

Question 34

Main Group Elements

Answer 34

groups on the periodic table with properties which tend to be largely predictable based on their position on the table.

Have an “A” associated with the number.

Question 35

Transition Elements(or Metals)

Answer 35

elements whose properties tend to be less predictable based simply on their position on the periodic table.

Have a “B” associated with the number.

Question 36

Family(Group)

Answer 36

A column within a maingroup on the periodic table. Usually share similar properties.

Question 37

Noble Gases

Answer 37

Group 8A.

Mostly unreactive(stable) elements.

Helium(He), Neon(Ne), Argon(Ar), Krypton(Kr), Xenon(Xe), etc.

Question 38

Alkali Metals

Answer 38

Group 1A.

Reactive metals.

Tend to lose 1 electron and become a 1+ ion(cation).

Lithium(Li), potassium(K), rubidium(Rb), etc.

Question 39

Alkaline Earth Metals

Answer 39

Group 2A.

Fairly reactive but less than Alkali Metals.

Tend to lose 2 electrons and become a 2+ ion(cation).

Calciums(Ca), Magnesium(Mg), Strontium(Sr), Barium(Ba), etc.

Question 40

Halogens

Answer 40

Group 7A.

Very reactive nonmetals.

Tend to gain 1 electron to become a 1- ion(anion)

Chlorine(Cl), Bromine(Br), Iodine(I), Fluorine(F), etc

Question 41

Ions and the periodic table

Answer 41

1. A main-group metal tends to lose electrons, forming a cation with the same number of electrons as the nearest noble gas.
2. A main-group nonmetal tends to gain electrons, forming an anion with the same number of electrons as the nearest noble gas.

Question 42

Atomic Mass(Amu)

Answer 42

the average mass of the isotopes that compose an element weighted according to the natural abundance of each isotope.

Atomic Mass(Amu) = (fraction of isotope 1 * mass of isotope 1) + (Fraction of Isotope 2 * mass of isotope 2)… = X amu

Located directly beneath the symbol for the elements on the periodic table.

Question 43

Mass Spectrometry

Answer 43

a technique that separates particles according to their mass.

Abundance of an Isotope = (100%/% Isotope 1 + %Isotope 1) * 100% = relative % to other ions of same element.

Question 44

Mole(mol)

Answer 44

the amount of material containing 6.02214 * 10^23 particles.

The value of a mol is equal to the number of atoms in exactly 12 grams of pure carbon-12.

12g C = 1 mol C atoms = 6.02214 * 10^23 C Atoms.

Question 45

Avogadro’s Number

Answer 45

Amedeo Avogadro.

6.02214 * 10^23(a mol)

Question 46

Molar Mass

Answer 46

1 mol of atoms of an element.

An elements molar mass in grams per mole is numerically equal to the elements atomic mass units.

Question 47

Conversion between mass and moles

Answer 47

Copper(Cu) has 63.55 amu and a molar mass of 63.55 g/mol.

63.55g Copper(Cu) = 1 mol of Copper(Cu) = 6.02214 * 10^23 Cu atoms.

Question 48

Volume

Answer 48

V=4/3(pie)(r)^3

Question 49

Diatomic

Answer 49

Have, No, Fear, Of, Ice, Cold, Beer

H2,N2,F2,O2,I2,Cl2,Br2

H,N,O and Group 7A are Diatomic