TKA 8th grade honors physical science - exam 2nd quarter review

*do not solely depend on this for your exam, not all information is promised to be correct* made by Ashley Arrington and Kirsten Tenore you're welcome
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Terms in this set (...)

democritus
first person to even mention the possibility that matter is formed of small pieces that couldn't be cut into smaller pieces, and used to word 'atomos'
daltons theory
he inferred that atoms had certain characteristics, began to propose an atomic theory and model for atoms, most of which are still accepted today.
JJ Thomson
he found that atoms contain even smaller things, negatively charged particles, and reasoned that atoms must also contain positively charged particles and described what an atom must look like compared to berries in a muffin
Rutherford
JJ Thompson student who challenged Thompson model using the gold foil experiment. this formed the thought of the centre of the atom, or nucleus, as well as the idea of protons. hsi atom model showed that an atom was mostly empty space, with electrons orbiting around in random order
Borhs Model
he was both a student of Thompson and Rutherford revised the atomic model yet again, to show that electrons could only have specific amounts of energy, making them move in specific orbits, as of an onions rings'
Atomic number
every atom of an element has the same number of protons, thus atomic number = number of protons
Isotopes / mass #
atoms with the same # of protons and a different number of neutrons are isotopes, mass # is the same number of protons and neutrons in the nucleus of an atom
Mendelevs Work
he knew that some elements have similar chemical and physical properties, he determined elements melting points, density, and color, atomic mass, and more characterizations to form the first periodic table of the elements, organizing elements in order of increasing atomic mass.
atomic mass
is the average mass of all the isotopes of an element
the modern periodic table
is organized by atomic number
periods
horizontal rows on periodic table
families / groups
vertical rows on the periodic table
families stand in groups
reading an elements square
How elements form in stars
nuclear fusion
the sun is mostly made up of this element
hydrogen
Physical / chemical properties of metals
physical- shininess, malleability, ductility, conductivity, magnitsm

chemical- reactivity, corrosion
metal family names and properties
alkali metals (first group in periodic table, react by loosing one electron)

alkaline earth metals (second group in periodic table, react by loosing 2 electrons)

transition metals (groups 3 - 12 less reactive of the metals)

metals in mixed groups (select few elements in groups 13-15, not very reactive)

Lanthsnides (two rows of elements placed below the periodic table, more recently discovered)
Physical / chemical properties of nonmetals
poor conductors to heat and electricity, reactive with other elements, solid nonmetals are dull and brittle
nonmetal family names and properties
carbon (group 14, can gain, loose, or share 4 electrons when reacting with other elements)

nitrogen (group 15, typically gain or share 3 electrons to react)

oxygen (group 16, typically gain or share 2 electrons to react)

halogen (group 17, typically gains or shares 1 electron to react)

noble gases (group 18, do not need to react to become stable, for they are stable alone)
metalloids
have both characteristics of metals and nonmetals ex silicone
valence electrons
those electrons that are held in the outer shell of an atom and are held most loosely and have the highest energy level
electron dot diagrams
includes the symbol for the element and dots representing valence electrons surrounding it
how the periodic table works
organized by atomic number
3 groups in periodic table
metals, non metals, metalliods
ionic vs covalent bonds
ionic bonds are attractions btwn oppositely charged particles and are btwn nonmetals and metals, covalent bonds are just btwn nonmetals
how ions form
this forms when a metal combines with a nonmetal
polyatomic ions
ions that are made of more than one atom
chemical formulas
Combination of symbols that shows the ratio of elements in a compound
chemical subscripts
Tells you the ratio of the element in a compound
naming ionic compounds
the name of the positive ion comes first, followed by the name of the negative ion
properties of ionic compounds
1. Ionic Crystals
2. High melting points
3. Electrical conductivity
covalent bonds
The chemical bond formed when 2 or more nonmetals share their valence electrons
covalent compound properties
1. Lower melting and boiling points
2. Poor conductivity
what are the 2 types of covalent bonds?
polar and non polar
metallic bonding / alloys
An attraction between a positive metal ion and the electrons surrounding it
Alloy- a mixture made of 2 or more metals
steel =
steel = Iron + Carbon + Nickel + Crominum
matter
Anything that has mass and takes up space
matter properties
Chemical and physical properties
physical change
Any change that alters the form or appearance of a substance but does not make anew substance
chemical change
A change in matter that produces one or more new substances.
5 evedences of chemical reaction
1. A color change may occur
2. A precipitate may form
Precipitate- a solid that forms from solution during a chemical reaction
3. A gas may be produced
4. Light may be produced
5. Heat may be produced
exothermic reacton
A reaction in which energy is being released in the form of heat
endothermic reactions
A reaction in which energy is being absorbed (cold)
chemical equations
A short way to show a chemical reaction using symbols instead of words
reactants / products
Reactants- The substance you have in the beginning. On the left side of the arrow
Products- When the reaction in complete and you have a new substance. On the right side on the arrow
conservation of mass - open vs closed system
Conservation of mass- during a chemical reaction matter is not created nor destroyed
Open system- matter can enter or escape to the surroundings
Closed system- matter is not allowed to enter or leave
balancing chemical equations
1. Write the equation
2. Count the atoms
3. Use coefficients to balance atoms
coeficient
A number placed in front of a chemical formula to balance it
3 classifications of chemical reaction
1. Synthesis- When 2 or more elements or compounds combine to make a more complex substance
2. Decomposition- Breaks down compounds into simpler products
3. Replacement- When one element replaces another in a compound or when two elements in a different compounds trade places
5 factors that alter the rate of a chemical reaction
1. Surface area- When you increase the surface area more particles are exposed to react
2. Temperature- increasing the temp will increase the rate of reaction
3. Concentration- the amount of a substance in a given volume of another
4. Catalysts- a material that increases the rate of reaction by lowering the activation energy needed
enzymes- biological catalysts
5. Inhibitors- a material used to decrease a rate of reaction
fire and fire safety
The best form of fire safety is fire prevention
Fuel, Oxygen, and Heat start a fire
Combustion- a rapid reaction between oxygen and fuel
solution = ________ + __________
solvent + solute
solute
The part present in the smallest amount and gets dissolved
solvent
The part present in the largest amount
colloids
A mixture containing small undissolved particles that do not settle out, but are large enough to scatter light such as milk
suspensions
A mixture in which the particles can be seen and easily separated by settling or filtration
solutes lower _________ point of solvents
freezing
solutes ___________ boiling point of a solvent
raise
dilute vs concentrated solution
Dilute- a mixture that only has a little amount of solute in it
Concentrated- a lot of solute dissolved in the solvent
sloutbility - saturated / unsaturated
Saturated- When you have added so much solute that no more can dissolve
Unsaturated- When you can still dissolve more solute
pressure and temp effecting solubulity
Pressure- The higher the pressure of the gas over the solvent, the more gas that can be dissolve
Temp- Most solids solubility increases as the temperature increases
acids
1. Produces hydrogen ions
2. Taste sour
3. Reacts with metals and carbonates
4. Turns blue litmus paper red
bases
1. Produces hydroxide ions
2. Taste bitter
3. Feels slippery
4. Turns red litmus paper blue
5. Does not react with metals or carbonates
indiactors
A compound that changes color when it comes in contact with an acid or a base EX. Litmus paper
acids in solution form this
Hydrogen ions
bases in solution form this
Hydroxide ions (OH-)
what prooducts do an acid and a base make when they react
Water and a salt
digestion and Ph
Digestion- Breaks down the complex molecules into smaller molecules.
pH- A range of values from 0-14, 0 is the most acidic and 14 is the most basic, and 7 is nuetral
enzymes
A biological catalyts
metallic bond
forms when a metal combines with a metal