Chemistry Test😭

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 ​Double bond - two pairs of electrons shared between two atoms ​Triple 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. ​(ex. FeS + 2 HCl → 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 ​(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 → 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