Chapter 1.1-2.3 Flashcards
Law of Conservation of Matter
“There is no change in the total quantity of matter present when matter converts from one type (a chemical change or changes) to another” nor is matter ever lost during a chemical reaction
Mass vs Weight
Mass is constant wight changes based on gravity
Symbolic Domain
-Chemical symbols, formulas & equations
-Graphs, drawings, and calculations
Describes what happens in the macroscopic domain in terms of the components of the microscopic donatain
Microscopic vs Macroscopic Domain
Macroscopic: The realm of everyday things that are large enough to be sensed directly by human sight or touch
Microscopic: The levels of individual atoms and molecules
What is Plasma
Plasma: A gaseous state of matter that contains an appreciable amount of electrically charged particles
Pure Substance
Types of Pure substances
-“has a constant composition. All specimens have exactly the same make”
-Types of Pure Substances:
- Elements: there are 118 elements - pure substances cannot be decomposed any further
- Compounds: Pure substances of 2 or more elements - more than 10 million
Mixture
-Combinations of 2 or more pure substances
-Each substance retains its own chemical identities
Type of Mixture: Heterogeneous
-Made of multiple substances
-Appearance is not uniform
- Portions of a sample have different composition and properties
Type of mixture: Homogeneous
“A homogeneous mixture is a mixture in which the composition is uniform throughout the mixture”.
How many elements make up 99% of earths crust? Name 5
Only 11.
- Oxygen
- Iron
- Chlorine
- Carbon
- sulfur
- calcium
-sodium
Fun Fact - Chemistry of a Cell phone
Almost 1/3 of naturally occurring elements are used to make a cell phone
Physical Properties of matter
“Physical properties can be observed or measured without changing the composition of matter”
(mass, weight, volume, and density)
Chemical properties and Chemical changes
Chemical properties: Characteristics that relate to how substances changes into another substance
(flammability, sensitivity to corrosion)
Chemical changes: occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances
Extensive properties and intensive properties
Extensive properties: Depend upon the quantity of the sample
(Mass, shape, VOLUME)
Intensive Properties: do not depend upon the quantity of the sample
(tempter, melting point, boiling point, density, color)
Measurements
Every measurement provides three kinds of information: the number, the unit, and the uncertainty
Solution vs Compound
“The key difference between compound and solution is that a compound contains two or more elements that are chemically bound together whereas a solution has few substances that do not chemically bound together as compounds do”.
Prefixes in Scientific notation
Mega-10^6
kilo-10^3
Centi-10^-2
milli-10^-3
Micro-10^-6
Mg vs mg
Mg=Megagram
mg=milligram
What are ml equivalent to
cm^3
Identify the three basic parts of a quantity
Meter, Kilogram, Kelvin
Describe the properties and units of length, mass, volume, density, temperature, and time
Length: Meter
Mass: Kilogram
Volume: meters cubed m^3
Density: Mass/volume - Intensive propertyaz n
Tempter: Kelvin
Time: second
Amount: Moles
Electrical current: Ampere
Define Accuracy and precision
Accurate is correct - errors due to systematic error
Precise is similar - random errors
If you measure 8.47 grams and 9.13 grams and the answer is 9 grams you are accurate
If you measure 3.47 grams and 3.43 grams and the answer is 9 grams you are precise
Distinguish exact and uncertain numbers
Counting is the only type of measurement that is free from uncertainty, provided the number of objects being counted does not change while the counting process is underway. The result of such a counting measurement is an example of an exact number.
Correctly represent uncertainty in quantities
In general, numerical scales such as the one on this graduated cylinder will permit measurements to one-tenth of the smallest scale division. The scale in this case has 1-mL divisions, and so volumes may be measured to the nearest 0.1 mL.
Every measurement has some uncertainty, which depends on the device used (and the user’s ability). All of the digits in a measurement, including the uncertain last digit, are called significant figures or significant digits. Note that zero may be a measured value; for example, if you stand on a scale that shows weight to the nearest pound and it shows “120,” then the 1 (hundreds), 2 (tens) and 0 (ones) are all significant (measured) values. Except leading zeros.
Memorize Prefix multipliers in the SI system
Sig Fig rules
For multi-step problems only apply sig figs after they are totally complete.
For equations that combine subtracting and division make sure to do it in steps and find sig figs along the way recording but wait to round until the end
law of definite proportions or the law of constant composition
all samples of a pure compound contain the same elements in the same proportion by mass.
fixedratio
law of multiple proportions
The law of multiple proportions states that when two elements react to form more than one compound, a fixed mass of one element will react with masses of the other element in a ratio of small, whole numbers
Dalton
The cathode ray tube experiment determined:
• Cathode rays are made of tiny particles w/ negative
charge
• Every material tested contained these same particles
• The charge/mass of these particles was -1.76 x 108 C/g
• Cathode rays are electrons
The Millikan oil drop experiment determined:
The the size of the charge on an electro
Rutherford’s gold foil experiment determined that?
The volume occupied by an atom must consist of a large amount of empty space.
A small, relatively heavy, positively charged body, the nucleus, must be at the center of each atom.Rutherford’s gold foil experiment determined that
isotopes
—atoms of the same element that differ in mass.
When Rutherford performed his gold foil experiment, he found that most of the alpha particles did pass through the atoms. However, some particles were deflected at large angles, even back towards the source.
the atom is mostly empty space with the protons and neutrons in a dense nucleus.
Is the charge of the nucleus negative or positive?
Positive
What charge does a neutron have?
It has zero charge!
Which two particles of the atom have nearly identical masses?
Proton and neutron
Which of the following statements about subatomic particles are true?
I. Protons and neutrons have charges of opposite signs but the same magnitude.
II. Protons and neutrons have about the same mass.
III. A neutral atom always has the same number of neutrons and electrons.
ll.
atomic number(Z) = number of protons
mass number(A) = number of protons+nutrons
A−Z= number of neutrons
The net charge on an atom of a given element changes as ______ are added or removed.
electrons
Danton’s Atomic Theory
Matter is composed of exceedingly small particles called atoms. An atom is the smallest unit of an element that can participate in a chemical change.
An element consists of only one type of atom, which has a mass that is characteristic of the element and is the same for all atoms of that element (Figure 2.2). A macroscopic sample of an element contains an incredibly large number of atoms, all of which have identical chemical properties.
Atoms of one element differ in properties from atoms of all other elements.
A compound consists of atoms of two or more elements combined in a small, whole-number ratio. In a given compound, the numbers of atoms of each of its elements are always present in the same ratio (Figure 2.3).
Atoms are neither created nor destroyed during a chemical change, but are instead rearranged to yield substances that are different from those present before the change (Figure 2.4).
Alpha Particles
Atoms are destructible!
• Alpha particles can combine w/
electrons to produce the
element helium, therefore alpha
particles are the positively
charged core of helium atoms
Subatomic particles
a particle smaller than an atom (e.g., a neutron) or a cluster of such particles (e.g., an alpha particle).
Discovery of the Nuetron
-Rutherford gold foil experiment-discover elections, neutrons, and protons
-physicist James Chadwick conducted an experiment in which he bombarded Beryllium with alpha particles from the natural radioactive decay of Polonium. The resulting radiation showed high penetration through a lead shield, which could not be explained via the particles known at that time.
Nuclei must contain particles with mass but no charge
