Science
A method of asking questions and finding answers.
Matter
Everything in the universe that has mass or occupies space.
Energy
The capacity to transfer heat or do work.
Chemistry
The study of composition, structure, and properties of matter.
Homogenous
A mixture that is uniform throug...
GENERAL AND ORGANIC CHEMISTRY QUESTIONS
AND ANSWERS 100%
Science
A method of asking questions and finding answers.
Matter
Everything in the universe that has mass or occupies space.
Energy
The capacity to transfer heat or do work.
Chemistry
The study of composition, structure, and properties of matter.
Homogenous
A mixture that is uniform throughout. (i.e. vinegar)
Heterogenous
A mixture that is NOT uniform throughout. (i.e. salad dressing)
Element
A pure substance that can not be broken down.
Compound
A substance consisting of two or more elements.
Law of Constant Composition
Every sample of a particular compound always contains the same elements in the same proportions.
Atom
The smallest representative particle of an element.
Filtration
A way to separate a substance by using a medium to hold one of the substances back. (i.e. using a
sift)
Distillation
Vaporizing volatile components and condensing them.
Intensive Properties
,Properties of matter independent of quantity. (i.e. color, malleability, melting temperature)
Extensive Properties
Properties that characterize how much of the object is present. (i.e. length, width, mass, volume)
Physical Properties
What is the atomic number of an element?
The atomic number of an element is the number of protons present in the nucleus of an atom of that
element.
Define an isotope and give an example.
Isotopes are variants of a chemical element that have the same number of protons but different numbers
of neutrons. An example is carbon, which has isotopes like Carbon-12 and Carbon-14.
What is the difference between a molecule and a compound?
A molecule is formed when two or more atoms bond chemically, while a compound is a molecule that
contains at least two different elements.
What is Avogadro’s number, and why is it important?
Avogadro’s number is 6.022×10236.022 \times 10^{23}, and it represents the number of atoms, ions, or
molecules in one mole of a substance.
Explain the law of conservation of mass with an example.
The law of conservation of mass states that mass cannot be created or destroyed in a chemical reaction.
For example, when hydrogen reacts with oxygen to form water, the total mass of hydrogen and oxygen
equals the mass of the water produced.
What is the pH scale, and what does it measure?
The pH scale measures the acidity or alkalinity of a solution, ranging from 0 (most acidic) to 14 (most
basic), with 7 being neutral.
What are the three states of matter, and how do they differ?
The three states of matter are solid, liquid, and gas. Solids have a fixed shape and volume, liquids have a
definite volume but take the shape of their container, and gases neither have a fixed shape nor a fixed
volume.
What is the difference between a physical change and a chemical change?
A physical change alters the form or appearance of a substance without changing its chemical
composition, whereas a chemical change results in the formation of new substances with different
chemical properties.
Define valence electrons and their significance in chemical bonding.
Valence electrons are the electrons in the outermost shell of an atom, and they determine an atom's ability
to form chemical bonds.
What is an ionic bond, and how does it differ from a covalent bond?
An ionic bond is formed when electrons are transferred from one atom to another, creating ions. A
covalent bond is formed when atoms share electrons.
Explain the concept of molarity and how it is calculated.
Molarity is a measure of the concentration of a solution, defined as moles of solute per liter of solution. It
,is calculated using the formula Molarity=moles of solutevolume of solution in liters\text{Molarity} =
\frac{\text{moles of solute}}{\text{volume of solution in liters}}.
What is the periodic table, and how is it organized?
The periodic table is a chart that organizes elements based on their atomic number, electron
configurations, and recurring chemical properties. Elements are arranged in rows (periods) and columns
(groups).
What are acids and bases according to the Arrhenius definition?
According to Arrhenius, acids are substances that increase the concentration of hydrogen ions (H+H^+) in
aqueous solutions, while bases increase the concentration of hydroxide ions (OH−OH^-).
What is a catalyst, and how does it affect a chemical reaction?
A catalyst is a substance that speeds up a chemical reaction without being consumed in the process. It
lowers the activation energy needed for the reaction to proceed.
Explain the difference between endothermic and exothermic reactions.
Endothermic reactions absorb energy from the surroundings, typically in the form of heat, while
exothermic reactions release energy.
What is the ideal gas law, and what does each term in the equation represent?
The ideal gas law is PV=nRTPV = nRT, where PP is pressure, VV is volume, nn is the number of moles,
RR is the ideal gas constant, and TT is temperature.
What are allotropes? Provide an example.
Allotropes are different forms of the same element in the same physical state. An example is carbon,
which exists as graphite, diamond, and graphene.
What is electrolysis, and what are its applications?
Electrolysis is a chemical process in which electrical energy is used to drive a non-spontaneous chemical
reaction. Applications include electroplating, extracting metals, and producing hydrogen gas.
What is the difference between a homogeneous and a heterogeneous mixture?
A homogeneous mixture has a uniform composition throughout, such as saltwater, while a heterogeneous
mixture has a non-uniform composition, such as a mixture of sand and iron filings.
Properties of a pure substance that can be observed or measured without changing the substance. (i.e.
color)
Density
The ratio of an object's mass to its volume.
Chemical Properties
A property of a substance that can only be observed by reacting it with another substance.
Solid Phase
Definite volume and shape.
Liquid Phase
, Definite volume, indefinite shape.
Gas Phase
Indefinite volume and shape.
Sublimation
Changing directly from a solid to a vapor (gas).
Deposition
Changing directly from a gas to a liquid (it was never a solid).
Kelvin Formula
K-273.15= C
Celsius Formula
C= (5/4)(F-32)
Fahrenheit Formula
F= (9/5)(C+32)
Thomson
Proposed new model for the atom through his plum pudding experiment. Discovered the electron.
Millikan
Discovered the charge of the electron (e-)
Mendeleev
Constructed the 1st periodic table of elements. Did not include the Noble Gases because they were non-
reactive and the table was ordered by reactivity.
Democritus
Believed matter is composed of indestructible particles (atoms).
Rutherford
Performed the gold foil experiment and determined that atoms are divisible.
ß particle
High energy electron in radiation.
∂ particle
A radioactive emission (charge: 2+) with the same mass of helium meniscus.
Nucleus
Positively charged center of the atom that contains most of the mass.
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