Unit 1: Ch 1-2 Flashcards
1
Q
Chemistry
A
- branch of science that seeks to understand the behavior of matter by studying the behavor of atoms & molecules
- includes identification of substances, investigation of properties & ways they interact, combine, & change, and use of these processes to form new substances
2
Q
Atoms
A
- submicroscopic particles that constitute the fundamental building blocks of ordinary matter
- free atoms are rare in nature, they typically bind in specific geometrical arrangements to form molecules
3
Q
Scientific method
A
Empirical meaning grounded on observation & experiment
4
Q
4 key characteristics of the scientific method
A
- observation
- formulation of hypotheses
- experimentation
- formulation of laws & theories
5
Q
Observations
A
Descriptions about the characteristics or behavior of nature & often lead scientists to formulate a hypothesis
6
Q
Who explained observations on combustion by hypothesizing that when a substance burns, it combines with a component of air?
A
Antoine Lavoisier
7
Q
Hypothesis
A
- a tentative interpretation or explanation of the observation
- falsifiable or refutability by observation
8
Q
Scientific law & Law of Conservation of Mass
A
- a brief statement that summarizes past observations & predicts future ones
- “in a chemical reaction, matter is neither created nor destroyed”
9
Q
Theory
A
- 1+ well-established hypotheses that may form the basis for a scientific theory
- a model that tries to explain not merely what nature does, but why
- validated by experiments, but cannot be conclusively proven
- ie: evolution by natural selection, quantum theory, general relativity, standard model of particle physics
10
Q
Matter
define, how is it classified, list classifications
A
- occupies space & has mass
- state (physical form) & composition (components)
- solid, liquid, gas, or plasma
11
Q
How does matter change with increasing temperature/energy
A
solid > liquid > gas or plasma
12
Q
Solid matter
describe structure, movement, types
A
- atoms/mols packed closely to each other in fixed location/defined shape (ie ice, aluminum, diamonds)
- can vibrate but do not move around or pass each other
- 2 types
-crystalline: patterns w/long-range, repeating solid matter. Ie table salt, diamonds
-amorphous: do not have any long-range order. Ie glass, plastic
13
Q
slide 10 image
A
14
Q
Liquid matter
A
- packed closely as they do in solid matter, but are free to move relative to each other
- fixed volume, but not a fixed shape
- ability to flow makes it assume the shape of its container
- ie water, alcohol, gasoline at room temperature
15
Q
Gaseous matter
A
- atoms/mols have a lot of space between them
- free to move relative to one another, making them compressible
- ie water, alcohol, gasoline at higher temperatures
16
Q
Plasma
A
- collection of free moving electrons & ions
- high energy required, temps & densities range from cool & tenuous to very hot & dense
- ie aurora, star, lightening
17
Q
Ion
A
atoms that have lost their electrons
18
Q
Bose-Einstein condensate (BEC)
A
- atoms/subatomic particles cooled to near absolute zero coalese into a single quantum mechanical entiry, a wave function on a near-macroscopic scale
- predicted in 1924 by Albert Einstein on the basis of the quantum formulations of the Indian Physicist Satyendra Nath Bose
19
Q
How is matter classified according to its composition?
A
elements, compounds & mixtures
20
Q
List & describe first division in the classification of matter
A
- pure substance
- made up of only 1 component, and its composition is invariant
- 2 types of substances: elements & compounds
- categorization based on whether it can be broken down (decomposed) into simpler substance
- mixture
- composed of 2+ components in proportions that can vary from one sample to another
- 2 types: hetergeneous & homogeneous
- Depends on how uniformly the substances within them mix
21
Q
Element
A
- composed of single type of atom (ie helium) that cannot be chemically broken down
- basic building blocks of matter
22
Q
Compound
A
- 2+ elements in fixed deinite proportions
- most are chemically reactive & combine with other elements to form compounds like water, sugar, etc.
23
Q
Heterogeneous mixture
A
- composition varies from one region of the mixture to another
- made of multiple substances whose presence can be seen
24
Q
Homogeneous mixture
A
- made of multiple substances but appears to be one substance
- all portions of a sample have the same composition and properties (ie sweetened tea)
- have uniform compositions because the atoms/mols that compose them mix uniformly
25
# add image for classif of matter, slide 16
26
How are mixtures separable?
components have different **physical or chemical properties**
27
How can heterogeneous mixtures be separated?
* decanting (ie pouring water off the top of sand sand)
* filtration (ie mixture through filter)
28
How can homogeneous mixtures of liquids usually be separated?
* **distillation**: moisture is heated to boil off more volatile (easily vaporable) liquid. The volatile liquid is then recondensed in a condenser and collected in a separate flask
* ie alcohol, desalination, crude oil refining
29
Physical change
* changes that alter only the **state or appearance of a substance**, but not composition
* atoms/mols do not change their identity (ie boiling water that changes from a liquid to a gas)
30
Chemical change
* **alter the composition of matter**
* atoms rearrange, transforming the original substances into different substances
* ie rusting of iron. iron oxidizes in the presence of oxygen from the air to form iron oxide
31
Physical property
* property that a substance **displays without changing it composition**
* ie odor, taste, color, appearance, melting point, density. water changing from ice>liquid>steam
32
Chemical property
* a substance that **displays only by changing its composition via a chemical change** (or chemical reaction)
* ie corrosiveness, acidity, toxicity, flammability of gasoline
33
Energy
* the **capacity to do work**
* fundamental part of physical & chemical change
34
Work
the action of a force through a distance
35
Kinetic energy
energy associated with the motion of an object
36
Potential energy
* energy associated with the position or composition of an object
* systems with high potential energy **tend to change in a direction that lowers their potential energy**, releasing energy into the surroundings
37
Thermal energy
* energy associated with the **temperature** of an object
* a type of **kinetic** energy because it arises from the **motion or vibration of the individual atoms or mols** that make up an object
38
Law of conservation of energy
Energy may be transformed but it is never created or destroyed, it is always **conserved** in a physical or chemical change
39
What type of energy is chemical energy?
Potential energy because it is stored energy that could potentially be released
40
2 most common unit systems used
Metric & English
41
What unit system do scientists use & what basic units are used?
* International System of Units (SI)
* 7 basic units
- length / Meter / m
- mass / Kilogram / kg
- time / Second / s
- temp / Kelvin / K
- amt of substance / Mole / mol
- electric current / Ampere / A
- luminous intensity / candela / cd
| Based on the metric system
## Footnote
Systeme International d'Unites (SI)
42
Meter (m)
* length
* 1/10,000,000
* 1 m = 39.37 inches (1 yard = 36 inches)
* the distance light travels through a vacuum in a certain period of time
* measurements: ruler
43
Mass (kg)/(g)
* 1 kg = 2,205 lb
* 1 g = 1/1000 kg
* measurements: balance or scale
44
Duration (s)
* seconds (s)
* 1 s = period of time it takes for a specific # of radiation events of a specific transition from celsuim-133
* measurements: chromometer or time piece
45
Temperature
* kelvin (K)
* measure of the avg amount of kinetic energy of the atoms/mols that compose the matter
- assigns 0 K (absolute 0) to the coldest temp possible
- **temp at which molecular motion stops**. Lower temps do not exist
- temp determines the direction of thermal energy transfer (heat): trx from **hot to cold** objects
* measurements: thermometor or thermocouple
46
Celcius formula
ºC= (ºF -32) / 1.8
47
Kelvin formula
K = ºC + 273.15
48
# slide 26, Temperature Scales
49
Mole
* amount/count of a substance
50
# Verify if this is needed, slide 27
Units of measurements multipliers
51
Derived units
Combination of other units
52
Volume formula
Volume = L x W x H
53
Density
| formula, define, expression
* D = mass / volume
* ratio of mass to volume
* commonly expressed as g/cm3 or g/mL
* affects if a substance will sink or float. The less dense substance floats
54
Intensive property
* bulk property
* does not depend on the system size or the amount of material in the system
* ie temp, density
55
Extensive property
* dependent on the amount of substance, increasing or decreasing as the amount of material changes
* ie mass, volume
56
The density of copper decreases as temp increases. What happens as it is warmed from room temp to 95ºC?
the sample expands
57
What is the **precision** of a measurement depend on?
The **instrument** used to make the measurement
58
How is the **preservation** of precision during calculations accomplished?
* **Significant figures**
* The greater the # of sig figs, the greater the certainty of the measurement
59
Significant figures rules
## Footnote
Ref Ch1 slide 31
* all nonzero digits are significant
* interior zeroes are significant
* leading zeroes are NOT significant
* trailing zeroes are as follows:
- after a decimal are signif (ie 45.**000**)
- before a decimal are signif (ie 14**0**.00)
- before an implied decimal are ambiguous and should be avoided (ie 12**00**)
- a decimal point placed after one or more trailing zeroes is signif (ie 1200**.**)
60
# Rules
Sig fig calc rules:
1. Multiplication & division
2. Add'n & subtraction
3. Rounding
## Footnote
Ch1, slides 33-34
1. result carries the **same # of sig figs** as the factor with the fewest sig figs
2. result carries the **same # of decimal places** as the quantity with the fewest decimal points
3. round down if the leftmost digit is **4 or less**; up if **5 or more**. Do not round intermediate steps
61
Exact numbers
* have an unlimited # of sig figs
62
Accuracy
## Footnote
Ch1, slide 35
* how close the measured value is to the actual value
* accurate only if they are close to the actual value
63
Precision
* how close a series of measurements are to one another or how reproducible they are
* precise if they are consistent with one another
64
# Ch1 slide 35 image
65
Random error
error that has the equal probability of being too high or too low
66
Systematic error
error that tends toward being either too high or too low
67
Little systematic error or random error
accurate and precise
68
Dimensional analysis
## Footnote
1.7
* use of conversion factors to determine numerical quantity between different units
69
Robert Brown
* Scottish botonist
* **water-suspended particles of pollen grains** observed that the particles were in **continuous motion**
* Formulated a few hypotheses as to the **cause of the motion**
70
Albert Einstein
* developed a theory that **quantitatively explained** what was by then called **Brownian motion**
71
Jean Perrin
* tested Einstein's model & confirmed the model was valid
* awarded the Nobel Prize in Physics; **removed doubt about the partial nature of matter**
72
Leucippus & Democritus
* proposed that **matter was composed of small, indestructible particles**
* Democritus wrote, "Nothing exists except atoms and empty space; everything else is opinion"
* proposed that **different atoms exist, each a different shape & size, & they move randomly through empty space**
73
Plato & Atristotle
* did NOT embrace atomic ideas
* believed that matter had no smallest parts but was composed of various proportions of **fire, air, earth, & water**
74
John Dalton
* offered evidence that supported the early atomic ideas of Leucippus & Democritus, resulting in **Dalton's Atomic Theory**
75
Define atom
How many natural & synthetic elements have been identified?
* smallest identifiable unit of an element
* key to connecting macro/microscopic worlds
* ~91 different natural & 20 synthetic elements
76
List the 3 laws that led to the development & acceptance of the atomic theory
1. Law of conservation of mass
2. Law of definite proportions
3. Law of multiple proportions
77
Law of Conservation of Mass
* Antoine Lavoisier
* **matter is neither created nor destroyed**
* when a chemical reaction occurs, the total mass of the substances involved in the reaction does not change
78
Law of Definite Proportions
* all samples of a given compound, regardless of their source/preparation, have the **same proportions of their constituent elements**
* ie, when 18g of water is decomppsed, it always results in 16g O and 2g H
79
Law of Multiple Proportions
* when 2 elements form 2 different compounds, the **masses of 1st element that combine with 1g of other element can be expressed as a ratio of a small whole number**
* ie, an atom of A combines with either 1, 2, 3+ atoms of B (AB1, AB2, AB3, etc.)
80
Dalton's atomic theory
1. each element is composed of tiny, indestructible particles called **atoms**
2. all atoms of a given **element have the same mass & other properties that distinguish them** from the atoms of other atoms
3. atoms **combine in simple, whole-number ratios** to form compounds
4. atoms of one **element cannot change** into atoms of another element. In a chemical reaction, atoms only change the way that they are bound together with other atoms
81
J.J. Thompson
| significance, ratio
## Footnote
Ch2, slide 10-11
* used **cathode ray tube** to produce a beam of particles
* Discovered the following properties:
* travel in **straight lines**
* **independent** of the composition of the material from which they originate (the cathode)
* carry a **negative electrical charge**
* **discovered the electron**
82
Electron
a negatively charged, low mass particle present within all atoms
83
Discovery of the electron
| history, list properties
* J.J. Thompson's experiments using **partially evacuated** glass tube (cathode ray tube) to produce a **beam of particles** (cathode rays) that traveled from the **negatively charged electrode** to the positively charged (anode) one
* properties:
* travel in straight lines
* independent of the composition of the material from which they originate (the cathode)
* carry a negative electrical charge
84
Robert Millikan
* **oil drop experiment**, deduced the charge of a single electron
* by measuring the strength of the electric field required to halt the free fall of all drops, and the masses of the drops, he determined their **radii & density**
* calculated the charge of each drop, which is always a multiple of **-1.60x10^-19 coulombs (c)**, the fundamental charge of a single electron
85
Theoretical model
(plum-pudding model)
* J.J. Thompson proposed that the negatively charged electrons were small particles held within a positively charged sphere
* Rutherford **directed the positively charged alpha particles at gold foil and rcvd unexpected results**. Some penetrated, bounced back, deflected.
* Led to new model, the **nuclear theory**
86
Rutherford
* Concluded matter must **not be as uniform as it appears**. It must contain large **regions of empty space** dotted with **small regions of very dense matter**
* Created **nuclear theory**
87
3 parts of nuclear theory
1. most of the atoms mass & all of its positive charge are contained in 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 **protons** within the nucleus, so that the atom is **electrically neutral**
88
T/F
All atoms are composed of the same subatomic particles
True
89
T/F
Protons & neutrons have nearly identical masses
True
90
T/F
The charge of the proton & the electron are equal in magnitude & opposite in signal and standardized as +1 and -1, the neutron has no charge
True
91
How is the mass of atoms and elements standardized?
* atomic mass unit (amu)
* **1/12th the mass of a carbon-12 atom, which has 6 protons & 6 neurons**
* results in both neutron & protons having a mass of approx 1 amu
92
T/F
For neutral atoms & elements, the # of protons & electrons will be inequal
False
They will be equal
93
# verify
How do you calculate the mass of an atom or element?
* Add the protons & neutrons
* ie Helium-4 (2 protons & 2 neutrons) = 4 amu
94
Isotpope
Atoms with the same number of protons but a **different number of neutrons**
95
The relative amount of each different isotope in a naturally occurring sample of a given element is roughly constant.
What are these percentages called?
Natural abundance of the isotope
## Footnote
Advcances in mass spec allow for accurate measurements that reveal very small but signif variations in isotopes
96
What are the following symbols?
A
Z
X
* A = mass (protons + neutrons)
* Z = atomic number
* X = chemical symbol (ie H)
97
T/F
During chemical change, atoms can lose or gain electrons and become charged ions.
True
98
T/F
For a given element, the size of an atom is the same for all of the element's isotope
True
99
T/F
For a given element, the size of an isotope with more neutrons is larger than one with fewer neutrons
False
100
Periodic Law
* **Mendeleev** organized known elements in a table, arranging the rows so that **elements with similar properties fall in the same vertical columns**
* when elements are arranged in order of increasing mass certain sets of properties recur periodically
101
How is modern periodic table organized & classified?
* listed in order of **increasing atomic number** & organized by:
* metals
* nonmetals
* metalloids
* also divided into
* **main-group elements**: properties tend to be largely **predictable** based on their position in the table. **Letter A elements**
* **transition element/metals**: properties tend to be **less predictable** based simply on their position in the table. **Letter B elements**
102
Metals
| location on periodic table, characteristics
* **lower-left & middle** of the periodic table
* good conductors of **heat & electricity**
* **malleable**
* **ductile** (can be drawn into wires)
* **shiny**
* **lose electrons (oxidize)** when they undergo chemical change
103
Nonmetals
| location on periodic table, description, characteristics
* **upper-right** side of the periodic table
* **17 nonmetals**
* 5 solids
* 1 liquid (Br)
* 11 gases
* poor conductors of heat & electricity
* not ductile or malleable
* **gain electron (reduce) when they undergo chemical changes**
104
Metalloids / semimetals
| location on periodic table, characteristics
* lie along the **zigzag** diagonal line that divides metals & nonmetals
* exhibit **mixed properties**
* several are classified as **semiconductors** because of their intermediate electrical conductivity
105
Noble gas
* group 8A
* **mostly unreactive**
* ie helium, neon, argon. krypton, xenon, radon are radioactive
106
Alkali metals
* group 1A
* **very reactive** metals
* ie lithium, potassium, rubidium, caesium
107
Halogens
* group 7A
* **very reactive nonmetals**
* gain 1 electron and form 1- ions
* always found in nature as **salt**
* **flourine**, pale-yellow gas
* **chlorine**, greenish-yellow gas with pungent odor
* **bromine**, red-brown liquid that evap to gas
* **iodine**, purple solide that sublimes (solid to gas state)
108
Main-group metals
* tend to lose electrons, forming a **cation** with the same # of electrons as the nearest noble gas
109
Main-group nonmetals
* tend to gain electrons, forming an **anion** with the same number of electrons as the nearest noble gas
110
Alkali metal ions
* lose 1 electron and form 1+ ions
111
Alkaline earth metal ions
* group 2A
* tend to lose 2 electrons and form 2+ ions
112
Halogen ions
* gain 1 electron and form 1- ions
113
Oxygen family nonmetal ions
* gain 2 electrons and form 2- ions
114
Ions on the periodic table
| main-group & transition elements
* main-group elements:
* **cations**: charge is equal to the group #
* **anions**: charge is equal to the group # minus 8
* transition elements:
* form various different ions w/different charges
115
Atomic mass
| aka atomic weight, standard atomic weight
* directly beneath element's symbol
* represents **avg mass of the isotopes** that compose the element, weighted according to the natural abundance of each isotope
116
Mass spectrometry
* measures the **mass-to-charge ratio** of 1+ atoms/mols present in a sample
* used to calculate the **exact atomic mass** & **relative abundance of isotope** of isotope in a sample
