Chemistry TestЁЯШн
What is the principle of conservation of mass? When is it true? What does it mean?
Matter is not created or destroyed True in all reactions The amount of matter in a chemical reaction remains the same
An ionic bond forms as a result of the attraction between
Oppositely charged ions
Explain the difference between polar covalent and nonpolar covalent.
Polar is unequally and nonpolar is equal
How is the chemical formula for an ionic compound written? What goes first? What goes last?
Positive first the negative
What is a single bond? A double bond? A triple bond?
Single bond - one pair of electrons shared between two atoms тАЛDouble bond - two pairs of electrons shared between two atoms тАЛTriple bond - three pairs of electrons shared between two atoms
Which two types of reactions could be considered opposites?
Synthesis and decomposition
Potassium Sulfide is an ionic compound with the chemical formula K2S. How many Potassium atoms are in this compound? How many Sulfur? How do you know?
Theres two potassiums and one sulfur. The 2 tells you there are two potassiums for every one sulfur ion
What is double replacement
When ions are exchanged between two compound. тАЛ(ex. FeS + 2 HCl тЖТ FeCl2 + H2S)
What is an enzyme?
a substance produced by a living organism that acts as a catalyst to bring about a specific biochemical reaction.
The ___ of a compound shows the ratio of elements present in the compound.
chemical formula
Which group of the periodic table contains elements with two valence electrons?
Group 2
One nonmetal is
Fluorine
What is a precipitate?
A solid
What is a valence electron? Why is it important?
A valence electron is an electron that is in the highest occupied energy level of an atom. A valence electron is important they play a key role in chemical reactions.
Which groups/families of the periodic table contain the most reactive elements?
Alkali Metals Halogens - most reactive nonmetals ex. Fluorine, Chlorine, Bromine, Iodine, and Astatine's
If the products formed from the burning candle are mostly carbon (C), carbon dioxide (CO2), and water (H2O), what elements were in the reactants? How do you know?
Carbon, Hydrogen, and oxygen were in the reactants because carbon dioxide and carbon contain oxygen, water contains hydrogen, and carbon dioxide and water contain oxygen.
Compare and contrast chemical and physical changes
Chemical changes occur when existing bonds break and new bonds form. Physical changes - alter the form or appearance but does not make a new substance тАЛ(ex, ice melting)
What do you call a chemical reaction that uses symbols instead of words?
Chemical equation
Explain the difference between endothermic and exothermic reactions.
Exothermic reactions releases more heat. Endothermic reactions absorb more heat than it releases,
Bonds that form between two nonmetal atoms usually are_ bonds
covalent
two nonmetals is
covalent
A chemical bond formed when two atoms share electrons is called a(n)
covalent bond
What type of reaction is FeS + 2 HCl FeCl2 + H2S?
double replacement
What is a polyatomic ion?
ions that are made of more than one atom
Ionic compounds are electrically
neutral
What's is single replacement
one element replaces another element in a compound.
What is synthesis?
two or more elements or compounds combine that make a complex substance
What is decomposition?
when compounds break down into simpler produces (ex. 2 H2O2 тЖТ 2 H2O + O2)
When ions having a positive charge form bonds with ions having a negative charge, the charge on the resulting compound is
zero
