Gen Chem Exam 1 Flashcards
Chemistry
The study of the composition, structure, properties, and reactions of matter.
Chemical
A substance that always has the same composition and properties wherever it is found.
Elements
Pure substances from which all other things are built.
Elements can not…
be broken down into simpler substances
What are examples of elements?
ALL elements on the periodic table!
Chemical Symbol
Represents the names of the elements (1-2 letters)
What is the chemical symbol for gold?
Au
What is the chemical symbol for aluminum?
Al
How many elements are on the periodic table?
118
Elements on the periodic table are in order of…
Increasing atomic mass
What is the difference between periods and groups?
Periods: Horizontal rows
Groups: Vertical columns
What does group A on the periodic table represent?
Representative Elements
What does group B on the periodic table represent?
Transition Elements
What is group 1A?
Alkali Metals (metals) - VERY reactive
What is group 2A?
Alkaline Earth Metals (metals) - Reactive
Is group 1A or 2A more reactive?
1A
What is group 7A?
Halogens (metalloids and nonmetals)
What is group 8A?
The Noble Gases (gases)
Metals
Shiny, ductile, and conduct heat/electricity
What is the one metal that is not a solid?
Mercury (Hg) = Liquid
Metalloids
-Contain properties of metals and nonmetals.
-Used/modified as semiconductors and insulators
What is the order of best conductors?
- Metal
- Metalloids
- Nonmetals
Nonmetals
-Dull, brittle, and poor conductors
-Good insulators
Nonmetals have low…
densities and melting points
Atom
The smallest particle of an element that retains the characteristics of the same element.
Daltons Atomic Theory
- All matter is made up of atoms.
- Atoms in one element are the same/different than those in another element.
- Atoms can be combined to form compounds.
- Atoms can be combined, separated, and rearranged in chemical reactions.
Compounds have a constant…
Composition
JJ Thompson’s Cathode Ray
- Cathode ray contains negative charged particles.
- The particles have a smaller mass than an atom
= electrons
Was JJ Thompson’s Cathode Ray experiment accepted?
Yes, but was controversial at first.
Thompson’s Plum Pudding Model
- The plum pudding modeled an atom
- Electrons are protons are randomly distributed in a positively charged cloud.
Alike charges ___, while opposite charges___
Repel, Attract
Rutherford’s Gold Foil Experiment (1911)
- Positive charged particles were aimed at gold foil
- Most particles went straight though the foil
- Some particles were occasionally deflected
Gold Foil Experiment conclusion….
There must be a small, dense, (+) charged nucleus in the atom that deflects the (+) charged particles when close.
Nucleus
Center of the atom that contains protons and neutrons
What does the nucleus represent?
The mass of the atom
Atomic Mass Unit (amu)
1 amu = 1/12 the mass of a carbon12 atom
or
1 Dalton in biology
Proton
-p or p+
-charge of 1+
- mass = 1
- Located in the nucleus
Neutron
- n or n0
- charge of 0
- mass = 1
- Located in the nucleus
Electron
- (e-)
- charge of 1-
- mass = 0
- Located outside the nucleus
What do all atoms of the same element have?
The same # of protons and the same atomic #
Atomic Number
A whole number that helps locate and identify elements.
The atomic number =
The # of protons
Mass Number
The whole number that represents the total number of particles in the nucleus of an atom.
The mass number =
protons + neutrons
Does the mass number appear on the periodic table?
No
The number of protons =
The number of electrons
Ion
When the charge of an atom does not equal 0 (different number of electrons than protons).
Cation
- Positively charged
- More protons than electrons
Anion
- Negatively charged
- More electrons than protons
Isotopes
Atoms of the same element that have
- different number of neutrons
- different atomic mass number
What are isotopes distinguished by?
Atomic symbols (Mg24 vs Mg25)
Average Atomic Mass
The calculated atomic mass of all isotopes of an element.
(Mg24 + Mg25 +Mg26 = avg atomic mass)
Protons + Neutrons =
Atomic Mass
The energy of an atom is determined by…
Electrons
Electrical Energy
Energy emitted as visible light and heat
-Travels through space
Emitted Energy =
Electromagnetic Radiation
What is an example of electrical energy?
An electric stove
Electromagnetic Radiation
Energy particles that move as waves
Photons
Particles of electromagnetic radiation
Wavelength
Distance between the peaks of waves
High energy radiation has ___ wave lengths
Short
Low energy radiation has ___ wave lengths
Long
Electromagnetic Spectrum
Arrangement of wavelengths of electromagnetic radation
The visible range of light is…
700-400 nm
Atomic Spectrum
Lines of color separated by dark areas
How is the atomic spectrum created?
When light from a heated element passes through a prism.
Each element has it’s own ___ spectrum.
unique
Energy Level
Each electrons specific energy in an atom
As electrons move farther away from the nucleus, their energy level…
Increases
The arrangment of electrons in energy levels determine…
Physical and chemical properties in an element
Energy emitted =
The difference between the two energy levels
As electrons move to a higher energy level…
Energy is absorbed
As electrons move to a lower energy level…
Light is emitted
Orbitals
3D volume where electrons have the highest chance of being found
S Orbital
- Found in all energy levels
- Holds up to 2 electrons
- Sphere shape
P Orbital
- Starts in energy level 2
-Holds up to 6 electrons - Dumbell shaped
D Orbital
- Starts in energy level 3
- Holds up to 10 electrons
- Two dumbells or donut shaped
Pauli Exclusion
Each orbital can hold up to 2 electrons
- Magnetic spins must cancel
Electron Configuration
Indicates placement of electrons in an atom.
- Fill energy and sub levels in order of increasing energy.
“Ground State”
Lowest energy configuration for that atom
Orbital Diagrams
Use boxes to show how electrons
- are arranged in orbitals
-fill orbitals from lowest to highest
-fill orbitals 1 sub level at a time
Cr and Cu are…
half filled in last S sub level to increase stability
Valence Electrons
Electrons in the outermost energy level
What orbitals do valence electrons occupy?
S and P
What does the A group number represent?
The number or valence electrons.
Lewis Symbol
Represent the valence electrons as dots placed on sides of the element symbol.
Atomic size
Increases down, decreases right
Atomic Radius
Distance between nucleus and outermost electrons
Ionization Energy
Energy required to remove one of the outermost electrons
Ionization energy decreases___ and increases ____.
down, right
Ionization energy is low for ___ and high for ___
metals, nonmetals
Metallic Character
increases down, decreases right (more prevalent for metals)
Matter
The material that makes up all things.
- Has mass and occupies space
How is matter classified?
According to it’s composition.
Pure Substance
Fixed/definite composition
What are the two types of pure substances?
Elements and Compounds
Element
Composed of 1 type of atom
What are examples of elements?
Any element on the periodic table.
Compound
Composed of 2+ elements, always combined in the same proportion
What are examples of compounds?
H20 (water), H2O2 (hydrogen peroxide), and NaCl (table salt)
Mixture
A type of matter that consists of
- 2+ physically mixed substances but not chemically combined
- 2+ substances in different proportions
- Can be separated in physical methods
What are the types of mixtures?
Homogenous and Heterogenous
Homogenous Mixture
A mixture with a composition that is uniform throughout
Are the different parts in a homogenous mixture visible?
No
A homogenous mixture can also be called a…
Solution
What are examples of homogenous mixtures?
Helium and aluminum foil
Heterogenous Mixture
A mixture whose composition varies from one part to another.
Are the different parts in a heterogenous mixture visible?
Yes
What are examples of heterogenous mixtures?
Pasta with sauce and the air we breath
What are the three types of matter?
Solid, liquid, gas
Solids have ___ shape and ___ volume
definite, definite
The particles in a solid are…
close together and have a fixed arrangment
What is the speed of particles in a solid?
Very slow
Liquids have a ___ shape and ___ volume
indefinite, definite
True or false: Liquids take on the shape of their container.
TRUE
The particles in a liquid are…
close together and mobile
What is the speed of particles in a liquid?
Moderatley fast
Gases have ___ shape and ___ volume.
indefinite, indefinite
True or false: Gases take on the same shape and volume as it’s container.
TRUE
The particles in a gas are…
Far apart and not uniform
What is the speed of particles in a gas?
VERY fast
Physical Properties
Characteristics observed/measured without changing the identity of a substance
What are examples of physical properties?
Shape, color, density, boiling/freezing points
Physical Change
- No change in identity/composition
- Change in state of matter
- Change in physical shape
What are examples of physical change?
Water boiling to form water vapor
Chemical Properties
Describe the ability of a substance to…
- Interact with other substances
- Change into a new substance
Chemical Change
An original substance is turned into a one or more new substances with
- New composition
- New chemical properties
- New physical properties
What are examples of chemical change?
Digesting food or fireworks exploding
Temperature
Measures how hot/cold an object is compared to another object
What does temperature indicate?
Heat flow between an object of a high temp and another of a lower temp
How is temperature measured?
Using a thermometer
What are temperature scales based on?
The difference between boiling and freezing points of water
What are temperature scales divided into?
Degrees
What are the boiling and freezing points of Celcius?
Boiling = 100
Freezing = 0
What are the boiling and freezing points of Fahrenheit?
Boiling = 212
Freezing = 32
What is absolute zero?
The coldest temperature possible
- 0 Kelvin
- -273.15 Celcius
Does Kelvin use a degree symbol or negative numers?
No
Energy
Ability to do work
- Makes objects move and stop
Work =
Force x Distance
What are the two types of energy?
Kinetic and Potential
Kinetic Energy
Energy of motion
What are examples of kinetic energy?
- Working out
- Driving a car on a road
- Water flowing over a dam
Potential Energy
Energy based on the position of an object or chemical composition of a substance
What are examples of potential energy?
- Compressed spring
- Water at the top of a dam
- Chemical bonds in gas, coal or food
Potential energy is converted into…
Kinetic Energy
Heat
Energy associated in the movement of particles
The faster the particles move, the ___ the heat/thermal energy
Higher
What is an example of heat?
An ice cube melting
- Energy is needed to change from solid to liquid
What are the SI units of energy?
Joule (J) or kilojoules (kJ)
How many kilojoules are in a Joule?
1000 kJ
What are the other units of energy?
calories (cal) or kilocalories (kcal)
How many kilocalories are in a calorie?
1000 kcal
Calorie
The amount of energy (heat) needed to raise the temperature of 1g H2O by 1 degree C
C (uppercase) stands for
Nutritional Calorie
How many calories are in a C?
1000 calories
How many C are in a kcal?
1
Calorimeters
Used to measure energy values of substances
Specific Heat
The amount of heat that raises the temperature of exactly 1g of a substance by 1 degree C
Specific Heat =
heat / mass x change in temperature
True of False: Each substance has a unique SH.
TRUE
Changes of State
Converting one state to another
Evaportation
Liquid molecules ON SURFACE gain enough energy to convert to a gas.
Condensation
Gas molecules lose energy to convert to a liquid
Boiling
ALL liquid molecules acquire energy to convert to gas.
- Bubbles appear throughout the liquid
Condensation and ___ are reversible processes.
Boiling
Melting
Solid changes to a liquid at the melting point temperature.
Freezing
Liquid changes to a solid at the freezing point temperature.
Melting and ___ are reversible processes.
Freezing
The melting and freezing point is…
0 degrees C
Heat of Fusion is the amount of heat
- Released when 1g of liquid freezes.
- Needed to melt 1g of solid
Heat of Vaporization is the amount of heat…
- Absorbed to change 1g of liquid to gas at the boiling point.
- Released when 1g of gas changes to liquid at the condensation point.
Heating Curve
A digram that shows temperature increase and change of state as heat is added.
Cooling Curve
A diagram that shows temperature decrease and change of state as heat is removed.
