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CHEM 121 > Chapter 2 - Atoms, Molecules, and Ions > Flashcards

Chapter 2 - Atoms, Molecules, and Ions Flashcards

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1
Q

What are the 4 elements?

A

Fire
Earth
Water
Air

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2
Q

What is Democritus, the early atomic theory?

A
  • divisibility of matter
  • used shape as atomic distinctions
  • atomos
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3
Q

What is atomos?

A

ultimate particlles

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4
Q

in 2000 years of Alchemy, what did they attempt?

A
  • attempts to turn metal into gold
  • in the hunt, prepared mineral acids and isolated elements such as mercury and sulfur
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5
Q

How do you find emeralds, fake emeralds?

A
  • take white lead and any glass
  • fuse them together in a crucible and then pour the mixture
  • add urine of an ass to this crystal
  • after 40 days, you will find emerals
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6
Q

Elements can’t be broken down into what?

A
  • 2 or more simpler substances
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7
Q

What is the law of conservation of mass by Lavoisier?

A
  • mass is neither created nor destroyed
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8
Q

What is the Law of definite proportions by Proust?

A
  • a given compound always contains exactly the same proportion of elements by mass

ex. CO2 always contains 2.66g of O for every g of C.

ex. water always contains 8g of O for every 1g os H

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9
Q

What is the law of multiple proportions by Dalton?

A

The law of multiple proportions states that whenever the same two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers

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10
Q

What are 4 components of Dalton’s Atomic Theory?

A
  1. each element is made up of tiny particles called atoms
  2. the atoms of a given element are “identical”; the atoms of different elements are different in some fundamental way
  3. chemical compounds are formed when atoms combine with each other. A given compound always has the same relative number and types of atoms
  4. chemical reactions involve the reorganization of atoms; changes in the way they are bound together.

Atoms themselves are not changed in a chemical reaction

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11
Q

What is one of the incorrect assumptions that Dalton made when he prepared the first table of atomic masses, based on the relative mass of elements in known compounds?

A

Known: water is 8 grams of oxygen for every 1 gram of hydrogen

  • the assumed formula was OH
  • assigned hydrogen a mass of 1 and oxygen a mass of 8
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12
Q

What is Avogadro’s hypothesis?

A

“at the same T and P, equal volumes of different gases contain same number of particles”

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13
Q

What is the Cathode-ray tube experiment that J.J. Thomson did?

A
  • produced a beam of electrons in an evacuated tube
  • deflected beam with an applied electrical field
  • measured charge-to-mass ratio of an electron (negatively charged)
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14
Q

Explain the plum pudding model?

A
  • electrons distributed randomly in a diffuse positive cloud
  • just like raisins dispersed in pudding
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15
Q

What are the 3 types of radiation and review what they are?

A
  • gamma rays (g): high energy light
  • beta particles (b): high speed e-‘s
  • alpha particles (a): He2+ ions (mass 7300 x larger than the e-)
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16
Q

try the mass-density-volume-displacement question

  • Canadian $0.10 and $0.25 coins are made of pure nickel which has a density of 8.902 g/cm3. Suppose each dime weighs 2.02g and each quarter weighs 5.05g. A small collection of dimes and quarters are submerged in 10.00mL of water in a graduated cylinder causing the water level to rise to the 15.11mL mark. What is the combined monetary value (in Can$) of those coins?
A

$0.10 -> 2.02g
$0.25 -> 5.05g

Calculated $/g -> ($0.10/2.02g) = 0.049 $/g

  1. Volume of coins: 15.11mL - 10mL = 5.11mL
    For water: (5.11mL)(1cm3/1mL) = 5.11cm3
  2. Mass of coins - use density -> 8.902 g/cm3
    (8.902 g/cm3)(5.11cm3) = 45.49g
  3. Monetary Value: (45.49g)(0.0495 $/g) = $2.25 (many combinations)
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17
Q

review Rutherford’s gold foil experiment

A
  • experiment to deduce smth about the distribution of electrons in the atom
  • bombarded gold foil with high energy a particles (+ve)
  • Expectations: a particles would pass straight through with little or no deflection

Results and Observations:
- most particles passed straight through
- some with a slight deflection
- some with large angle deflection
- some bounced back

“it was almost as if you fired a 15-inch shell into a piece of tissue paper and it came back and hit you”

Conclusions:
- atom is mostly empty space
- massive positive center (nucleus): Thomson was incorrect
- e-‘s moved around the nucleus at a relatively large distance

  • an atom is neutral (#e- = #p+)
18
Q

If atoms are made of the same components, why do different atoms have different chemical properties?

A
  • the chemical properties are due to the number and arrangement of electrons
  • different elements have different number of protons, neutrons, and electrons
19
Q

What does the atomic number tell us?

A
  • the # of protons in the nucleus = # of electrons in a neutral atom
20
Q

how do you get the atomic mass number?

A
  • # of protons + # of neutrons
21
Q

How do you get the # of neutrons?

A

atomic mass number - the atomic number

22
Q

What are isotopes?

A
  • atoms with the same atomic # (same element) but different mass #
  • the same number of protons but a different number of neutrons
  • isotopes can be used in fusion
  • the sun can do it but not us because it requires a VERY high temperature and pressure that is hard to do on earth
23
Q

What is an element?

A

a pure substance with only one type of aotm

a) a collection (aggregate) of individual atoms

23
Q

What is an element?

A

a pure substance with only one type of aotm

a) a collection (aggregate) of individual atoms
- ex. Ag, Mg, Fe, He…

b) elements that occur as molecules
- ex. H2, O2, N2, P4, S8, F2, Cl2, Br2, I2

c) allotropes

24
Q

What are allotropes?

A
  • different structural forms of an element
25
Q

What is a compound?

A

a pure substance with two or more different aotms

  • ex. CO2, H2O. NaCl, Ag2CrO4
26
Q

What are molecules?

A
  • combination of atoms and represented by chemical formulae
27
Q

What is the structural formula?

A
  • indicates individual bonds
  • may also indicate molecular shape
28
Q

what are ions?

A
  • form when a neutral species gains or loses one or more electrons
29
Q

What is an anion?

A
  • a negatively charged molecule (or element)
  • the number of electrons is greater than the number of protons
  • ex. Cl-
  • ex. S+2e- = S2-
30
Q

What is a cation?

A
  • a positively charged molecule (or element)
  • the number of electrons is smaller than the number of protons
  • ex. Na+
    -ex. Mg = Mg2+ + 2e-
31
Q

What are the prefixes from 1-8?

A

mono-
di-
tri-
tetra-
penta-
hexa-
hepta-
octa-

32
Q

name these acids w/out oxygen
HF
HCl
HBr
HI
HCN
H2S

A
  • hydrofluoric acid
  • hydrochloric acid
  • hydrobromic acid
  • hydroiodic acid
  • hydrocyanic acid
  • hydrosulfuric acid
33
Q

name these acids w/ oxygen
HNO3
HNO2
H2SO4
H2SO3
H3PO4
HC2H3O2

A
  • nitric acid
  • nitrous acid
  • sulfuric acid
  • sulfurous acid
  • phosphoril acid
  • acetic acid
34
Q

What are covalent bonds?

A
  • two atoms share one or more pairs of electrons
  • atoms in molecules are held together by covalent bonds
  • a molecule is the simplest particle or unit that represents that pure substance
  • covalent bonds tend to form between nonmetallic elements
  • covalent compounds (molecules) are usually a combination of nonmetallic elements
  • ex. CO2, H2O, NO2
35
Q

What are ionic bonds resulting from

A
  • results from the electrostatic attraction between oppositely charged ions
  • ionic solids have a geometrical arrangement of ions that maximizes the attraction between opposite charges and minimizes the repulsion between like charges
  • ionic compounds are usually a combination of a metal plus a nonmetal (or two polyatomic ions)
36
Q

What kind of atoms tend to form cations?

A

metallic atoms

37
Q

what kind of atoms tend to form anions?

A

nonmetallic atoms

38
Q

Which side are the metallic elements situated at on the periodic table?

A

left side

39
Q

which side are the nonmetallic elements situated at on the periodic table?

A

right side

40
Q

are the majority of elements metallic or nonmetallic?

A

metallic

41
Q

As you go across a row, what happens to the number of protons and electrons

A

they both increase by one each element

CHEM 121 (5 decks)

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