CHEM 110 - MIDTERM #1 Flashcards
What kind of science is Chemistry?
Central Science - it joins together all the sciences (physics & biology)
What is the scientific method?
Systematic approach to research (observation -> representation -> interpretation)
What is the difference between law and theory?
Law: concise statement of a relationship between phenomena that is always the same under the same conditions (F = ma)
Theory: unifying principle that explains a body of facts and/or those laws based on them (atomic theory)
Chemistry is the study of ______.
Matter
What is a substance?
Form of matter that has a definite composition and distinct properties (Ex: H2O)
What is a mixture?
Combination of 2 or more substances in which the substances retain their distinct identities
Difference between homogenous mixture & heterogenous mixture?
Homogenous mixture: mixture composition is the same throughout
Hetereogenous mixture: composition is not uniform throughout
What is are some examples of a homogenous mixture?
Air, Sea Water, Wine
What are some examples of heterogenous mixtures?
Chicken noodle soup, sand, oil & water
What is the physical means of separating a mixture?
Does not change the chemical composition of a substance (ie. distillation, ice melting, magnet)
What is the chemical means of separating a mixture?
Changing the chemical composition or identity of the substance(s) involved
An element cannot be separated into simpler substances by _______ means.
chemical
What is a compound?
A substance composed of atoms of two or more elements chemically united in fixed proportions
A compound can be separated into their pure elements by _____ means.
Chemical
What’s the difference between a mixture and a substance?
Mixture: combination of substances that can be separated by physical methods to form substances
Substances: form of matter with distinct properties composted of compounds and elements
Compounds can be separated via chemical methods to form ____.
Elements
3 States of Matter
Solid: dense shape
Liquid: more degrees of freedom
Gas: no shape, but occupy space all throughout
What is an example of chemical change?
Hydrogen burning in air to form water
What’s the difference between extensive and intensive properties?
Extensive: dependent on amount of matter
Intensive: does NOT dependent on matter
What are examples of extensive properties?
Mass, volume, length
What are examples of intensive properties?
Density, Color, Temperature
What is matter?
Anything that occupies space and has mass
What is weight?
Force that gravity exerts on an object
What SI unit measures the amount of substance?
Mole (mol)
Kilo-
1000 (10^3)
Milli-
1/1000 (10^-3)
Micro-
1/(10^6)
deci-
1/10 (10^-1)
centi-
1/100 (10^-2)
nano-
10^-9
mega-
10^6
pico-
10^-12
What is volume?
SI derived unit for volume is cubic meter (m^3) where 1 mL = 1 cm^3
What is density?
SI derived unit for density is kg/m^3
D = mass/volume
What are the units for density?
g/mL or g/cm^3
How do we find Kelvin (K) from using Celsius?
K = C + 273.15
What is 0 Celsius in Kelvin?
273.15
How do we find the degrees in Fahrenheit?
F = 9/5 x C + 32
What is scientific notation?
A convenient way of showing the # of significant figures in a value
When you multiply you ___ exponents.
add
When you divide exponents, you ___ exponents.
subtract
What are significant figures?
Any digit that is not zero ~ provides uncertainty and accuracy of a measurement
What is the rule for addition/subtraction with # of sig figs?
The answer cannot have more digits to the right of the decimal point than any of the original numbers (83.3333 + 1.1 = 90.4)
What is the rule for multiplication/division of sig figs?
The # of sig figs must be set by the original number that has the smallest number of sig figs (4.51 + 8.7777777 = 16.6)
What is the difference between accuracy and precision?
Accuracy: how close a measurement is to the true value
Precision: how close a set of measurements are to each other
Give an example of a compound
Sugar, water
Water boiling is an example of ___ change
physical
fertilizers help to increase agricultural production is an example of ____ change
chemical
the flashlight beam slowly gets dimmer and finally goes out is an example of ___ change
chemical
What is Dalton’s Atomic Theory?
1) Elements are composed of atoms
2) All atoms of an element are identical, have same size, mass and chemical properties
3) Compounds are composed of atoms of more than one element
4)A chemical reaction is the rearrangement of atoms (not creation or destruction - law of conservation of mass)
What is the law of conservation of mass?
Mass is not created or destroyed
What is Dalton’s Law of Multiple Proportions?
If 2 elements form more than one compound - the ratio of the masses of the 2nd element can be reduced to whole numbers
What was the finding of Rutherford’s Experiment (1908)?
1) Atoms positive charge is concentrated in the nucleus
2) Protons have an opposite charge (+) of an electron (-)
3) Mass of a proton = 1840 x mass of e- (1.67 x 10^-24 g) = protons are bigger than electrons
What is the atomic number (Z)?
number of protons in a nucleus and determines the identity of an element
What is the mass number (A)?
number of protons + neutrons
What are isotopes?
Atoms of the element with different numbers of neutrons in their nuclei
What is the first group and respective charge in the period table?
Alkali Metals (+1)
What is the second group of the periodic table with their respective charge?
Alkaline Earth Metals (+2)
What is the name of the 3rd-12th group in the periodic table?
Transition metals (varying charges)
What is the name of the 7th group of the periodic table and their respective charges?
Halogens (-1)
What is the name of the last group of the periodic table?
Noble gases
What is the difference between a period and a group?
period = row in the periodic table
group = column in the periodic table