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unit 3 chemistry
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the number of protons in the nucleus of an atom of an element
the total number of protons and neutrons in an atom's nucleus
pure substance that consists entirely of one type of atom
the smallest unit of an element that maintains the properties of that element
ability to reflect light
able to be hammered into thin sheets
the ease and speed with which an element combines, or reacts, with other substances
electrons on the outermost energy level of an atom (determines and elements reactivity)
a characteristic of a substance that can be observed without changing the identity of the substance
a region around the nucleus of an atom where electrons are likely to be found
one of two or more atoms with the same atomic number but with different numbers of neutrons
three groups of the periodic table
non-metals, metals and metalloids
properties of metals
☆ good conductors of electricity and heat ☆ ductile and malleable ☆ reaction with water is corrosion
properties of non-metals
☆ poor conductors ☆ not ductile or malleable ☆ brittle and dull ☆ many are gasses
properties of metalloids
☆ properties of metal and non-metals ☆ solids that are shiny or dull ☆ conduct heat but not as good as metals ☆ ductile and malleable
they have similar properties, organized into columns
horizontal rows, don’t have similar properties
Hydrogen has 2 valence electrons and is a gas at room temperature. It's very reactive and is never found uncombined.
☆ alkali metals ☆ 1 valence electron ☆ react with air to form caustic metal oxides ☆ shiny, consistency of clay
☆ alkaline earth metals ☆ 2 valence electrons ☆ very reactive, (not as much as group1) ☆ never found uncombined in nature ☆ shiny, soft (but harder than group 1 metals)
☆ transition metals ☆ 1 or 2 valence electrons ☆ moderate (ex: Fe) to low reactivity (ex: Au) ☆ good conductors of heat and electricity ☆ compounds are usually brightly colored
☆ boron family ☆ 3 valence electrons ☆ moderately reactive ☆ includes a metalloid (boron) and the rest are metals
☆ carbon family ☆ 4 valence electrons ☆ unreactive ☆ includes a non-metal (carbon), metalloids and metals
☆ nitrogen family ☆ 5 valence electrons ☆ tend to share electrons when they bond ☆ moderately reactive
☆ oxygen family ☆ 6 valence electrons ☆ moderately reactive (oxygen is very reactive) ☆ most elements in this family share electrons when forming compounds
☆ halogen family ☆ 7 valence electrons ☆ react with alkali metals to form salts ☆ strong odors and interesting colors ☆ halogen atoms only need to gain 1 electron to fill their outermost energy level
☆ noble gases ☆ 8 valence electrons ☆ extremely unreactive ☆ inactive because their outermost energy level is full, called inert because they aren’t ready to combine with other elements
they stay the same over time
will eventually decay into a different nucleus
when a nucleus emits a particle and changes identity, that process is called
Isotopes that are unstable and undergo radioactive decay are called
the most stable neutron to proton ratio
elements with a large number of protons are most stable when their neutron to proton ratio is ____. The more protons an element has, the ____ this ratio needs to be for the nucleus to be stable.
types of decay
alpha, beta - , and beta +
too many neutrons compared with protons
too many protons compared with neutrons
charge of +1, no mass, when they collide with an electron, both this particle and the electron get annihilated
when the nucleus is too big overall, it can become more stable by losing both protons and neutrons
has 2 protons and 2 neutrons, same as the nucleus of a helium-4 atom
splitting a nucleus into smaller parts, ex: power plants
combining nuclei to make something bigger, ex: stars
How many valence electrons does fluorine (F) have?
How many valence electrons does aluminium (Al) have?
How many energy levels does phosphorus (P) have?
Iron-50 has ___ protons and ___ neutrons.
A calcium ion has a charge of +2 and a mass of 40. How many electrons does it have?
An oxygen ion has a charge of -2 and a mass of 17. How many protons does it have?
Strontium (Sr) shares common properties with what other element?
All of the following are properties of metals EXCEPT a. brittle b. conducts elecricity well c. malleable d. lustrous
An isotope will undergo beta minus (electron) decay when
Its neutron to proton ratio is too high to be stable
A positron decay occurs, and the daughter isotope is Manganese-55. What was the parent isotope?
What particle is emitted when Barium-140 decays to Lanthanum-140?
What particle is emitted when Potassium-38 decays to Argon-38?