Exam 1 Flashcards
What is a homogeneous mixture?
Homogeneous mixtures have uniform composition throughout
What is a heterogeneous micture?
heterogeneous mixtures do not have uniform composition throughout
What is John Dalton’s atomic theory?
-All matter is composed of small particles called atoms
-Atoms of a given element are identical in mass and properties
-Atoms of different elements have different masses and properties
-Atoms combine in simple whole-number ratios to form compounds
-Chemical reactions involve the rearrangement of atoms, not their creation or destruction
What are the 3 subatomic particles?
-Protons
-Neutrons
-Electrons
What is the mass of an element determined by?
The sum of protons and neutrons
What are covalent bonds?
Covalent bonds involve the sharing of electrons between atoms
What are hydrogen bonds?
Hydrogen bonds are intermolecular forces that occur between 2 water molecules
Why is water cohesive?
Due to hydrogen bonding
Is water polar?
Yes. It forms strong intermolecular bonds with itself
Is water a universal solvent?
Yes
Equation to get Celsius from Farenheit
C = (F-3)(5/9)
T/F: Exact numbers limit the number of significant figures in a calculated result
False
What scales are used to measure temperature?
Farenheit, Celsius, Kelvin
What is temperature a measure of?
The kinetic energy of molecules
Does heat transfer from cold to hot, or hot to cold?
Heat always transfers from a hotter object to a colder one
Equation to get Farenheit from Celsius
F = (9/5)(C) + 32
Equation to get temperature in Kelvin from Celsius
K = C+273
What is the Law of Constant Composition (Definite Proportions)?
All samples of a pure compound contain the same elements in the same proportion by mass
T/F: The composition of compounds always consistent, regardless of how or where they are formed
True
What do significant figures always include?
-Nonzero digits
-Captive zeros
-Trailing zeros (when right to decimal point, when in scientific notation)
What do significant figures not always include?
-Leading zeros
-Trailing zeros (when left to a decimal point)
When multiplying/dividing, is the answer rounded to the smallest number of decimal places, or the smallest number of sig figs?
The smallest number of sig figs
When adding/subtracting, is the answer rounded to the smallest number of decimal places, or the smallest number of sig figs?
The smallest number of decimal places
What is the density formula?
d = (m/v)
What can density be used for?
Density can be used to determine whether an object will float or sink in a liquid
What did J.J. Thompson experiment with?
Cathode ray tubes
What did J.J. Thompson’s experiments lead to?
The discovery that atoms contain small, negatively charged particles called electrons. No matter what the metal was, the cathode ray tubes would get the same results (deflected towards the positive plate)
T/F: Electrons are heavier than atoms
False. Electrons are way lighter than atoms.
What did Millikan experiment with?
oil drops
What did Millikan’s experiments lead to?
The discovery that there is a fundamental electric charge (the charge of the electron)
What was the oil drop charge in Millikan’s experiments?
1.6 x 10^-19
What is the mass of the electron?
9.10 x 10^-31 kg
What did Rutherford Experiment with?
Gold Foil
What were the results of Rutherford’s experiments?
Atoms have a small, dense, positively charged nucleus; the positively charged particles within the nucleus are called protons (a - alpha particles are positively charged)
Do protons, neutrons, or electrons occupy most of the atom’s volume?
Electrons
T/F: Samples that have the same mass ratio are not necessarily the same substance
True
What is the Law of Multiple Proportions?
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
What subatomic particles are located in the nucleus?
Protons and neutrons
What are isotopes?
Atoms of the same element with different masses
Who were neutrons discovered by?
James Chadwick
T/F: The nucleus contains almost all the mass of an atom
True
What is the diameter of an atom?
10^-10
What is the diameter of the nucleus
10^-15
Greek prefix - Centi
1 x 10^-2
Greek prefix Milli:
1 x 10^-3
Greek prefix Micro
1 x 10^-6
Greek prefix Nano
1 x 10^-9
Greek prefix Pico
1 x 10^-12
What is the speed of light?
c = 2.998 x 10^8 m/s
What is the relationship between wavelength and frequency?
Wavelength and frequency are inversely proportional. As one increases, the other decreases
What is wavelength?
The distance between two consecutive peaks of a wave
What is frequency?
The number of wavelengths that pass a given point per unit time, measured in Hertz (Hz)
What is the equation for the relationship between wavelength and frequency?
c=λν
What is amplitude?
Amplitude is the height of the wave from its midpoint to its peak or trough. (Related to the energy and intensity of the wave)
T/F: Amplitude is related to the frequency or wavelength of a wave
False
What is the order of the electromagnetic spectrum, from longest wavelength/lowest frequency to shortest wavelength/highest frequency?
Radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays
T/F: Visible light is a small part of the electromagnetic spectrum
True
What is the relationship between energy and frequency?
Energy and frequency are directly proportional. Higher frequency waves have higher energy
What is the equation for energy?
E = hv
What is Planck’s constant?
(6.626 x 10^-34 Js)
What is the photoelectric effect?
The photoelectric effect occurs when light of a certain frequency hits a metal surface and ejects electrons
What is blackbody radiation?
The emission of light from an idealized object that absorbs all incident radiation. This spectrum depends on the temperature of the object
What is spectroscopy?
The study of the interaction between light and matter
T/F: Electrons move from ground state to excited state due to electricity
True
When does emission of photons occur?
When electrons return to the ground state from the excited state
What is continuous spectra?
Produced by dense materials, unbroken series of wavelengths
What is line spectra?
Produced by gases at low pressure, narrow line widths.
What is the Rydberg equation?
look at notes
What is the Bohr model?
It introduced the concept of quantized orbits for electrons, where electrons do not emit radiation. Explained the line spectra of hydrogen
What is the difference between physical change and chemical change?
Physical change alters the form or appearance of a substance without changing its chemical composition. In a chemical change, the kind of matter changes and at least one new substance with new properties is formed.
Examples of physical change
Melting ice to water, boiling water, freezing water
Examples of chemical change
Burning wood, cooking, rusting, rotting
