Science Fall 2019 exam ch. 4-7
Which of the following is a chemical equation that accurately represents what happens when sulfur and oxygen react to form sulfur trioxide?
2S + 302 ---> 2SO3
Beryllium, Be, and chlorine, Cl, form a binary ionic compound with a one-to-two ratio of beryllium ions to chloride ions. The formula for the compound is
BeCl2
The standard on which the atomic mass unit is based is the mass of a
Carbon-12 atom
Which of the following does not state what the arrow means in a chemical equation?
Conserves
Which of the following Group 1A is the most reactive? Cs (cesium), Li (lithium), K (potassium), or Na (sodium)
Cs (cesium)
When two atoms of the same nonmetal react, they often form a(an)
Diatomic molecule
Which halogen is most like to react?
F (florine)
Which of the following groups contain three elements with stable electron configurations?
Helium, Xenon, Neon
Fluorine, F, forms a binary ionic compound with lithium, Li. What is the name of this compound?
Lithium Fluoride
Which of the following is a balanced chemical equation for the synthesis of NaBr from Na and Br2?
Na + Br2 ---> 2NaBr
Which of the following compounds does not contain molecules?
NaCl
The substances that undergo change in a chemical reaction are called
Reactants
What is the difference between an atom in the ground state and an atom in an excited state?
The atom in an excited state has more energy and is less stable than the atom in the ground state.
Suppose an atom has a mass number of 23. Which statement is true beyond any doubt?
The number of protons in the nucleus does not equal the number of neutrons
Which of the following is unique for any given element?
The number of protons.
In the compound MgCl2, the subscript 2 indicates that
There are two chloride ions for each magnesium ion.
The elements most likely to form more than one type of ion are the
Transition Metals
In the name carbon dioxide, the prefix of the second word indicates that a molecule of carbon dioxide contains
Two oxygen atoms
A _____ is an electron that is that is in the highest occupied energy level of an atom and is used for chemical bonding of atoms.
Valence Electrons
The unit for atomic mass is
amu
To keep them from reacting, some highly reactive elements are stored in
argon
Which of the following gases emit colors when an electric current is applied?
argon and krypton
One twelfth the mass of a carbon-12 atom is used to define a(an)
atomic mass unit
Moving from left to right across a row of the periodic table, which of the following values increases by exactly one from element to element?
atomic number
The number of protons in one atom of an element is that element's
atomic number
To find the number of neutrons in an atom, you would subtract
atomic number from mass number
Which element is found in most of the compounds in your body except for water?
carbon
A representation of a chemical reaction in which the reactants and the products are expressed is a/an
chemical equation
A _____ shows what elements a compound contains and the ratio of the atoms or ions of the elements in the compound.
chemical formula
Which subatomic particle has a negative charge?
electron
In a polar covalent bond,
electrons are not shared equally between atoms
A member of the boron family has three valence electrons, while a member of the nitrogen family has?
five
Which elements are all halogens, react easily with metals, and are all nonmetals?
fluorine, chlorine, and iodine
At room temperature, none of the metals are
gases
Alkali metals, alkaline earth metals, and aluminum all form ions with positive chares equal to the
group number
Ionization energies tend to
increase from left to right across a period
Among the alkali metals, the tendency to react with other substances
increase from top to bottom within the group
As you move from left to right across a period, the number of valence electrons
increases
Typically, atoms gain or lose electrons to achieve
ionization
The name iron (II)indicates that a compound contains
iron ions with a 2+ charge
What are oxygen-17 and oxygen-18?
isotopes of oxygen.
How was Bohr's atomic model similar to Rutherford's model?
it described a nucleus surrounded by a large volume of space
In Niels Bohr's model of the atom, electrons move
like planets orbiting the sun
Mendeleev arranged the known chemical elements in a table according to increasing
mass
These are ductile, malleable, and are good conductors of electric current.
metals
Group 7A of the periodic table contains the
most reactive nonmetals
The glowing of a neon light is caused by electrons emitting energy as they
move from higher to lower energy levels
Two highly reactive elements in Period 2 are the metal lithium and the
nonmetal fluorine
Atoms of the most reactive elements tend to have
one or seven valence electrons
What do scientists use to predict the locations of electrons in atoms?
probability
In a period table, a set of properties repeats from
row to row
Which element is found in nature only in compounds?
sodium
Which phrase best describes a metallic bond?
the attraction between a metal cation and a shared pool of electrons
The usefulness of Mendeleev's periodic table was confirmed by
the discovery of elements with predicted properties
What can you assume has happened if an electron moves to a higher energy level?
the electron has gained energy
What does the electron cloud model describe?
the most likely locations of electrons in atoms
In an electron dot diagram, the symbol for an element is used to represent
the nucleus and all non-valence electrons
The tendency of an element to react is closely related to
the number of valence electrons in atoms of the element
The atomic mass of an element is
the weighted average of the masses of an element's isotopes
Which list of elements contains only metals?
tin, copper, cesium
The formation of an ionic bond involves the
transfer of electrons
Mendeleev gave the name eka-aluminum to an
unknown element he predicted would have properties similar to those of aluminum
