Competency 1.0 The Structure and Behavior of Matter Flashcards
Mass
A measure of the amount of matter in an object
How is mass measured?
The units of mass is measured in 2 different ways
1. In SI units it is measured in kilograms
- In English units it is measured in pounds (not to be confused with weight)
Weight
The measure of the force of gravity
not to be confused with mass!
What is a physical property of a substance?
- It’s density
- Color
- Hardness
- Viscosity
- Resistivity
- Solubility
- Ductility
What is density?
The mass of an object made of a substance divided by it volume
Equation: D =m/V
Chemical properties
Describes the ability of substances to be changed into new substances
Ex: Iron + air = rust (a chemical change as iron has different properties from rust)
Phase of matter
Refers to its three possible states
- Solid (has a definite shape and volume)
- Liquid (has a definite volume but takes shape of its container)
- Gas (will spread to occupy the entire space it is in)
Kinetic Theory of Matter
States that all matter consists of atoms or molecules in a state of constant motion
What is a plasma?
A partially ionized gas in which some of the electrons are not bound to any atoms or molecules.
They are the most common form of matter in the universe because stars are composed of plasmas.
They are electrically conductive.
What are the 4 physical properties of a gas?
- Temperature (T)
- Volume (V)
- Mass (n)
- Pressure (P)
Temperature
Is measured by a thermometer in either Fahrenheit or Celsius degrees
The SI unit for temperature is “kelvin” (k)
The average kinetic energy of atoms or molecules in a gas determines its temperature.
The lowest unit of temperature is 0kelvin and = an absence of molecular motion
Mass
Is measured in moles (n) which is the number of molecules in a gas
Mass is expressed and calculated in terms of Avogadro’s number: 1n = 6.02 x 10²³
What is SI?
The international system of units maintained by the International Bureau of Weights and Measures in Severes, France
Also known as the Metric System
Pressure
The pressure of a gas is a measure of the force it exerts on the wall of a container divided by the area of the wall.
Equation: P= F/A
The SI unit of force = Newton
The SI unit of pressure = Pascal
The Ideal Gas Law or Combined Gas Law
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A combination of Boyles law, Charles Law and Gay-Lussacs Law
Represented by this equation:
P¹V¹ P²V²
−−− = −−−−
T² T²
Boyles Law
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The temperature is constant and the pressure and volume are inversely related. If the volume decreases the pressure of the gas will increase because the particles will collide more frequently with each other.
Charles Law
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Pressure is constant and volume and temperature are directly related. If the temperature increases the kinetic energy of the particles increases causing the volume to increase.
Ex. A balloon will get bigger when hotter and smaller when colder.
Gay-Lussacs Law
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The volume is constant and amount is the same when you heat the gas the pressure will increase. Ex. Gas inside a metal container:The temperature will cause the particles to move faster inside the container and since the container is constant and can’t be stretched the particles will hit the side with greater force causing an increase in pressure.
John Daltons Atomic Model
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Made from observations in 1780s
- Matter is made up of atoms
- Atoms of an element are similar to each other
- Atoms of different elements are different from each other
- Atoms combine with each other to form new kinds of compounds
William Crookes
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In 1870s created “cathode rays” in a vacuum tube by connecting a high voltage battery to an anode and cathode
J. J. Thomson
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In 1896 discovered the electron
He also developed the “plum pudding” model of the atom. In this model the atom consists of electrons equally mixed in a sphere of positive material.
Plums= electrons pudding = positively charged matter
Ernest Rutherfords Atomic Model
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- Most of an atom consists of empty space
- At the center of an atom is the nucleus that contains most of the mass and all of the positive charge of the atom.
- The region of the space outside the nucleus is occupied by electrons
- The atom is neutral because the positive charge on the nucleus equals sum of the negative charges on the electrons.
Niels Bohr Model of the Atom
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In 1913 based on discoveries in quantum mechanics
- Electrons orbit the nucleus, but only in discrete orbits or energy levels
- Electrons don’t emit radiation when orbiting the nucleus
- When an electron moves from an outer orbit or higher energy level to an inner orbit or lower energy level, it emits a photon with an energy equal to the energy difference.
Compound
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A thing that is composed of two or more elements that have been chemically combined
Ex: water = hydrogen + oxygen
Element
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A substance that cannot be broken down into other substances
There are currently 118 elements on the periodic table built up by increasing the number of protons and neutrons in the nucleus.
Molecule
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The smallest particle of a substance that can exist independently and has all the properties of that substance.
Ex: a water molecule = 2 hydrogen atoms and 1 oxygen atom (chemical formula = H2O)
Mixture
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A combination of two or more substances in which the substances keep their own properties. Unlike a compound, they can be separated again by physical means.
Ex: a fruit salad
The four common compounds
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- Acids
- Bases
- Salts
- Oxides
They are classified according to their characteristics
Acids
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Contain hydrogen ions (H+), they also have a sour taste
4 common acids:
NAME FORMULA USE
1. Sulfuric Acid H₂SO₄ Fertilizers, explosives
2. Nitric Acid HNO₃ Medicines, alcohol
3. Carbonic Acid H₂CO₃ Soft drinks
4. Acetic Acid HC₂H₃O₂ plastics, film, rubber
Bases
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Contain hydroxyl ions (OH-), have a bitter taste and can be slippery
4 common bases:
NAME FORMULA USE
1. Sodium hydroxide NaOH Soap, paper
2. Ammonium hydroxide NH₄OH deodorants
3. Potassium hydroxide KOH Soaps, drugs, dyes
4. Calcium hydroxide Ca(OH)₂ cement, plaster
Indicator
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A substance that changes color when it comes in contact with an acid or base.
Ex: litmus paper
Blue litmus paper turns RED in an acid
Red litmus paper turns BLUE in a base
Neutral
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A substance that is neither acidic nor basic and they do not change the color of litmus paper.
Salt
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Formed when an acid and base combine chemically. Water is also formed. The process is called neutralization.
Examples:
1. Table salt NaCl Epsom salt, toothpaste
2. Calcium chloride CaCl₂ melt roadway ice
Oxides
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Compounds that are formed when oxygen combines with another element.
Example:
Rust is an oxide formed when oxygen combines with iron.
Chemical reaction (2 types)
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Occurs when one or more substances are
- Exothermic chemical reactions release energy
- Endothermic reactions require energy
Chemical equilibrium
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Occurs when the quantities of reactants and products are no longer changing but the reaction may still proceed forward and backward. The rate of forward reaction must equal the rate of backward reaction to create a “steady state”.
Nucleus
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The center of an atom
Protons
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The positive particles inside a nucleus. The mass of a proton is about 2,000 times that of the mass of an electron but the magnitude of the charge is the same.
Atomic number
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The number of protons in the nucleus of an atom. All atoms of the same element have the same atomic number. Atoms have no charge because the number of electrons moving around the nucleus equals the number of protons.
Neutrons
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The second particle in the nucleus of an atom. They are neutral and have no charge. They are slightly more massive than protons. The number of neutrons in a nucleus can vary.
A Substance
A material with uniform properties throughout
Ex: salt, steel, gold and water
Ex of a non-substance: Milk (appears uniform but is not due to fat particles)
Isotopes of an element
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Have the same number of protons in the nucleus but have a different number of neutrons.
Atomic Mass Units (AMUS)
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The mass of an element on the periodic table. An amu is equal to 1/12 of the mass of a carbon-12, the most common isotope of carbon. Carbon-12 has 6 protons, 6 neutrons and electrons.
Mass number
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The sum of protons and neutrons found in an atom.
Electrons
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Electrons occupy discrete energy levels, the ones closest to the nucleus have the least amount of energy. The Pauli Exclusion principle:
ENERGY LEVEL. NAME. #OF ELECTRONS
First K shell 2
Second L shell 8
Third M shell 18
Fourth N shell 32
Excited electrons
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Electrons that have absorbed energy and have moved farther away from the nucleus.
The Periodic Table of Elements
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An arrangement of elements in rows and columns
Arranged in numerical order by atomic number
Horizontal rows are called Periods1-7
Vertical columns are called Groups or Families
Key to Periodic Table
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Atomic number
2 ↕️
Electron Arrangement 4 6
Symbol of element ➡️ C
Average
12.0 ⬅️ Atomic mass
Carbon
Element name
3 Types of Elements
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- Metals
- Non-metals
- Metalloids
Metals
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All elements in group 1 are ALKALI METALS except hydrogen
All elements in group 2 are ALKALINE EARTH METALS
The transition elements are found in period 4-7 and groups 4-12
Alkali Metals
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Found in group 1
Are shiny, softer and less dense than other metals. They are the most chemically reactive.
Alkaline Earth Metals
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Are found in group 2
They are harder, denser, have higher melting points and are chemically active
Transition Elements (metals)
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Are found in period 4-7 and groups 4-12.
They are hard and have high melting points.
Compounds of these elements are colorful like silver, gold and Mercury.
Non metals
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Do not always share physical properties
They are dull, brittle, and are not good conductors of heat and electricity.
Includes:
Solids, gases and one liquid (bromine).
They have 4-8 electrons in their outermost energy levels and tend to attract electrons.
They react with metals and their outer levels are usually filled with 8 electrons.
Halogens
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Found in group 17. Combine readily with metals to form salts.
Substances formed from halogens are:
Table salt, toothpaste, and bleach
Noble Gases
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Found in group 18. Do not react chemically with other elements. Will only combine with other elements under very specific conditions. They are inert (inactive).
Metalloids
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Have properties in between metals and non-metals. Found in group 13-16 (but do not occupy the entire group). Arranged in stair steps across groups.
Physical properties of Metalloids
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- Solids having the appearance of metal
- White or gray but not shiny
- Conduct electricity but not as well as metals
Chemical properties of Metalloids
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- All have some characteristics of metals and nonmetals
2. Their properties do not follow patterns like metals and non metals. Each must be studied individually.
Semiconductor
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Has a conductivity between that of an insulator and a conductor.
Example is Silicon (the second element in Group14)
- sand is made of a silicon compound (silicon dioxide)
- silicon is used in the manufacture of glass and cement
Valence Electrons
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The outermost electrons in atoms.
They are the only electrons involved in the bonding process.
They determine the properties of the element.
Chemical Bond
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A force of attraction that holds atoms together. When atoms are bonded chemically they cease to have individual properties.
Covalent Bond
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Formed when two atoms share electrons in order to get completely filled shells.
Happens between nonmetals.
Ex: hydrogen gas (H₂)
Covalent compounds
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Compounds whose atoms are joined by covalent bonds.
Ex: table sugar, methane and ammonia
Ionic Bond
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A bond formed by the transfer of electrons from one atom to the other.
Happens when metals and nonmetals bond.
Ions
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Atoms with an unequal number of protons and electrons.
Can be positive (+) or negative (-)
If it has more protons than electrons it is (+)
If it has more electrons than protons it is (-)
Ionic compounds
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Compounds that result from the transfer of metal atoms to nonmetal atoms.
Ex: sodium chloride (table salt), sodium hydroxide (drain cleaner), potassium chloride (salt substitute)
Metallic Bonding
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Happens only in metals and gives them their unique properties such as their malleability and electrical conductivity.
Occurs because electrons in metals are not fixed to a nuclei and are free to move allowing an interaction between electrons and the metallic nuclei bonding the atoms together.
Hydrogen Bonding
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A force that acts between two molecules of a liquid or a solid and holds the molecules together.
Can occur within and between other molecules
Ex. A water molecule
Composition Reaction
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2 or more substances combined to form a compound
Ex:
A+B = AB
C+O₂ = CO₂
Decomposition Reaction
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A compound breaks down into two or more simpler substances.
Ex:
AB = A+B
2H₂O= 2H₂ + O₂
Single Replacement Reaction
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A free element replaces an element that is part of a compound
Ex:
A+BX ➡️ AX + B
CuSO₄ + Fe ➡️ FeSO₄ + Cu
Double Replacement Reaction
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Parts of two compounds replace each other. In this case the compounds seem to switch partners.
Ex:
AX + BY ➡️ AY + BX
HCl + NaOH ➡️ NaCl + H₂O
