Chapter 5
Copper is an example of a what?
A transition metal?
Periodic Law
An element's electron configuration determines its chemical properties. Therefore members of a group in the periodic table have similar chemical properties. THIS pattern of repeating properties is the PERIODIC LAW
Why are alkali metals only found in nature
Because they are so reactive, alkali metals are found in nature only in compounds
An element on the periodic table has two naturally occurring isotopes. One isotope has an atomic mass of about 10 amu. The other isotope has an atomic mass of about 11 amu. What is the name of this element?
Boron, with an atomic mass of 10.81
Why is the table of the elements shown in Figure 7 called a periodic table?
The table is called a periodic table because the properties of the elements repeat at regular intervals from row to row
How many valence electrons would an element with atomic number 113 have?
Three
Halogens
The elements in Group 7A. each halogen has seven valence electrons.
Group
each column on the periodic table is called a group
how many periods does the periodic table have?
seven
Alkali Metals
the elements in Group 1A. These metals have a single valence electron and are extremely reactive.
Noble gases
the elements in Group 8A are called noble gases. helium has two valence electrons. Each of the other noble gases has eight valence electrons
Mendeleev arranged the elements in his periodic table in order of...?
Mass
What information did Mendeleev have about the elements he organized into a periodic table?
Mendeleev knew their relative masses and properties
How did Mendeleev know where to leave the spaces in his table?
Mendeleev placed elements in the groups where they logically belonged bases on their properties
An element that is shiny and conducts electric current is like to be a?
Metal
How many of the elements shown are metals? how many are nonmetals? How many are metalloids?
0 metals, 5 nonmetals, and 3 metalloids.
In general what happens to the reactivity of elements in groups labeled A as atomic numbers increases across a period
Across a period from left to right, metals become less reactive and nonmetals become more reactive, excluding the elements in Group 8A.
The most reactive metals are the what?
Alkali Metals
Explain how the atomic mass of an element is affected by the distribution of its isotopes in nature?
An atomic mass is weighted average of the atomic masses of an element's isotopes. The distribution of the isotopes determines how much each isotope affects the weighted average
Which elements is a liquid at room temperature and which is a gas at room temperature?
Bromine is a liquid and chlorine is a gas.
Why are samples of the alkali metal cesium usually stored in argon gas?
Cesium is an extremely reactive metal; argon is an extremely unreactive nonmetal.
Which of the two halogens shown is more reactive? Give a reason for your answer/
Chlorine is more reactive than bromine because the reactivity of nonmetals increases from the bottom to the top of a group.
List three ways that the elements in the periodic table can be classified
Elements can be classified by their estate at room temperature; by whiter they exist in nature; and by wherever they are metals, nonmetals, or metalloids
Why don't the elements within an A group in the periodic table have identical properties
Elements in the same A group do not have identical properties because their valence electrons are in different energy levels.
Mendeleev's decision to leave gaps in his periodic table was supported by the discovery of what?
Gallium
Which elements are all gases at room temperature?
Group 8A
Why are halogens found in nature only in compounds?
Halogens are always found in nature in compounds because halogens are highly reactive nonmetals.
Elements that have the same number of valence electron are?
In the same group
Does selenium have more in common with sulfur or bromine? explain your answer/
Selenium has more in common with sulfur because they are in the same group and have the same number of valence electrons.
Which elements on the periodic table has chemical properties that are most similar to those of carbon?
Silicon
Why was it difficult to discover the noble gases
The noble gases were difficult to discover because they are colorless, odorless, and very rarely react.
Why is the table of elements vary from period to period
The number of elements per period varies because the number of available orbitals increases the energy level increases
if you know that an element is a solid at room temperature, do you have enough data to classify the element as a metal, metalloid, or nonmetal? If you know that the element is a gas at room temperature, do you have enough data? Explain the answers.
There is not enough data for the solid because solids at room temperature can be metals, nonmetals, or metalloids. There is enough data for the gas because there are no gaseous metals or metalloids at room temperature.
If you were trying to make a compound of noble gas xenon, would your use nitrogen or fluorine? Explain your choice.
You would choose fluorine because it is much more likely to react than nitrogen is.
Metals
are elements that are good conductors of electric current and heat
Nonmetals
are elements that are poor conductors of heat and electric current
Transition metal
are elements that form a bridge between the elements on the left and right sides of the table
Metalloids
are elements with proprieties that fall between those of metals and nonmetals
In a modern periodic table, elements are arranged in order of what?
atomic number
Periodic Table
is an arrangement of elements in columns bases on a set of properties that repeat from row to row
Valence Electron
is an electron that is in the highest occupied energy level of an atom
An atomic mass unit is what?
one twelfth the mass of a carbon-12 atoms
