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85 terms

Chemistry

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What are two factors that determine density?
Mass and volume
Matter
the "stuff" everything is made of, has mass and volume
Which state(s) of matter have a definite shape and volume?
Solid
Which state(s) of matter take the shape of their container?
Liquid and gas
Describe the change in energy and molecular arrangement in evaporation.
Energy is gained, and the molecules move farther apart
Describe the change in energy and molecular arrangement in condensation.
Energy is released, the molecules get closer together.
What causes phase changes to occur?
Absorbing or releasing heat
Are phase changes physical or chemical changes?
Physical
What are the 5 signs of a chemical change?
Color change, temperature change, pH change, gas production, precipitate formation
Element
Simplest substance, cannot be broken down by chemical or physical changes
Molecule
When one or more atoms (elements) chemically bond
Compound
When one or more DIFFERENT elements chemically bond
What numbers on the pH scale represent acids?
Under 7
Law of Conservation of Mass
Matter cannot be created nor destroyed, it can only change forms. In any chemical reaction, the mass of the reactants is the same as the mass of the products
What affect does adding heat have on the molecular motion and arrangement of molecules?
Adding heat increases speed and causes molecules to spread apart
What affect does removing heat have on the molecular motion and arrangement of molecules?
Removing heat decreases speed and causes molecules to get closer together.
Mixture
when two or more substances are mixed but not chemically combined
Heterogeneous Mixture
a mixture in which the substances are not mixed evenly throughout
Homogeneous Mixture
a mixture in which the substances are mixed evenly throughout
Solution
a homogeneous mixture in which one substance dissolves in another
Suspension
a mixture in which substances can "settle" out
Solute
the substance that gets dissolved
Solvent
the substance that does the dissolving
What factors increase the rate of dissolving?
Increasing temperature, stirring, increasing surface area
Chemical change
a change in matter that produces a new substance
Ion
an atom that gains or loses an electron
Isotope
an atom that gains or loses a neutron
If an atom was to gain or lose a proton, it would become
an different element
What are some properties of polymers?
Flexibility, ability to bounce, ability to absorb water
pH indicator
a compound that changes color in the presence of an acid or a base
What affect does pressure have on the boiling points of liquids?
Increasing pressure increases the boiling point
What affect does adding a solute have on the boiling point of liquids?
Adding a solute increases the boiling point
What affect does adding a solute have on the freezing point of liquids?
Adding a solute decreases the freezing point
Why does adding a solute increase the boiling point of a liquid?
In order to boil, the molecules in the liquid need to spread apart. When a solute is added, the liquid molecules have a harder time spreading apart because the solute molecules are in the way. So, more energy has to be added.
What phase changes are endothermic reactions?
Melting, Evaporation, Sublimation
What phase changes are exothermic?
Freezing, condensation, deposition
Endothermic Reaction
a reaction that absorbs or takes in energy
Exothermic Reaction
a reaction that releases or gives away energy
What happens to the surroundings of an endothermic reaction?
They get colder.
What happens to the surroundings of an exothermic reaction?
They get warmer.
Neutralization reaction
a reaction between an acid and a base that results in a more neutral product
What are the products of a neutralization reaction?
water and a salt
Is dissolving a chemical or physical change?
Physical
Sublimation
Solid to gas
Deposition
gas to solid
Condensation
gas to liquid
Evaporation
liquid to gas
Freezing
liquid to solid
Melting
Solid to liquid
What are some chemical properties?
Flamability, reactivity with an acid, reactivity with oxygen, type of chemical bonds, etc.
What are some physical properties?
Color, texture, luster, boiling point, freezing point, dissolving
The columns of elements on the Periodic Table
Groups or families
The rows of elements on the Periodic Table
Periods
The elements in the first column of the periodic table
Alkali metals
The elements in the second column of the Periodic Table
Alkaline Earth Metals
The elements in Groups 3 - 12 on the Periodic Table
Transition Metals
The elements located along the "staircase" on the Periodic Table
Metalloids
The elements that have 7 valence electrons
Halogens
The elements in the right-most column of the Periodic Table
Noble Gases
Metals are found on what side of the "staircase"?
Left
Nonmetals are found on what side of the "staircase"?
Right
What is the atomic number?
the number of protons an element has
Where would you find the atomic number?
In the box for the element on the Periodic Table, it is usually found above or in the upper right corner.
Why are elements organized into groups in the Periodic Table?
They have similar properties.
Unique Characteristics of the Alkali Metals
Very reactive and not found in nature in pure form. They are so soft you can cut them with a knife and are shiny and silver. They have 1 valence electron.
Unique Characteristics of the Alkaline Earth Metals
Slightly less reactive than Alkali metals but are more dense. They are silver in color and have 2 valence electrons.
Unique Characteristics of the Halogens
Poor conductors of heat and electricity. They form salts when they bond with metals. They have 7 valence electrons and are very reactive.
Unique Characteristics of the Noble Gases
Nonreactive, stable gases that have 8 valence electrons
Two rows were removed from the periodic table to keep it from getting too wide. What are these called
Lanthanide and Actinide Series
Unique Characteristics of the Lanthanides and Actinides
The rare earth metals are shiny and reactive. The 2nd row are all radioactive.
Why are the elements along the "staircase" called the metalloids?
They share properties of both metals and nonmetals.
What ions are associated with acids?
H+ or Hydrogen ions
What ions are asssociated with bases?
OH- or Hydroxide ions
What are the charges of protons, electrons, and neutrons?
Protons - +
Electrons - neg.
Neutrons - neutral
What are some methods that can be used to physically separate a mixture?
Dissolving, evaporating, sifting, magnets
Viscosity
The resistance of a liquid to move
Why do antacids work?
Antacids are a base. When you have too much stomach acid you can have a stomach ache. So, when the OH- ions in the antacid mix with the H+ ions in your stomach, they neutralize to form water and a salt.
Why do we add salt to icy roads in the winter?
Adding salt is adding a solute. When a solute is added, the freezing point is lowered. The salt gets in the way of the molecules from getting closer together/lining up and results in the temperature having to be lower for it to freeze. So, the ice will often melt when salt is added.
Why do we sweat?
When we sweat, the sweat evaporates from our skin. This occurs with the liquid sweat's molecules spread out and move faster in order to turn into a gas. This means that the molecules need to gain energy to evaporate. The molecules gain energy from our bodies, thus cooling us down. This is an endothermic reaction.
For the element Magnesium (Mg)...
Is it a metal, nonmetal, or metalloid?
What group is it a part of?
How many valence electrons does it have?
What is its reactivity like?
Metal, alkaline earth metal, 2 valence, very reactive
For the element Helium (He)...
Is it a metal, nonmetal, or metalloid?
What group is it a part of?
How many valence electrons does it have?
What is its reactivity like?
non metal, noble gas, 8 valence, not reactive/stable
For the element Chlorine (Cl)...
Is it a metal, nonmetal, or metalloid?
What group is it a part of?
How many valence electrons does it have?
What is its reactivity like?
non metal, halogen, 7 valence electrons, reactive/form salts with metals
For the element Gold (Au)...
Is it a metal, nonmetal, or metalloid?
What group is it a part of?
How many valence electrons does it have?
What is its reactivity like?
metal, transition metal, transition metals have 1 or 2 valence, good conductors of heat/electricity
For the element Tellurium (Te)....
Is it a metal, nonmetal, or metalloid?
What group is it a part of?
How many valence electrons does it have?
What is its reactivity like?
Metalloid, Oxygen Family, 6 valence, very reactive
On the tops of mountains (or at high elevations) there is a ___________ pressure so the boiling point of water ____________.
there is a LOWER pressure so the boiling point of water DECREASES. (Water can boil at a lower temperature)