Chemical compounds

Question 1

Chemical Compounds

Answer 1

material formed by chemically bonding two or more chemical elements

Question 2

Types of Compounds

Answer 2

Ionic
Molecular
Acids

Question 3

Positively charged ions are called cations because

Answer 3

they migrate towards the cathode (negative pole) in solution - they tend to lose electrons and form cations

Question 4

Negatively charged ions are called anions because

Answer 4

they migrate towards the positive pole (anode) and are therefore known as anions - non-metals tend to gain electrons and form anions

Question 5

Ionic compounds conduct electricity

Answer 5

when dissolved in water or when molten

Question 6

Examples of Ionic Compounds

Answer 6

NaCl (Sodium Chloride)
CaBr2 (Calcium Bromide)

Question 7

difference between a compound and a molecule

Answer 7

molecule is formed when two or more atoms join together chemically
compound is a molecule that contains at least two different elements

Question 8

Molecular compounds

Answer 8

combinations of non-metals
easy to identify, as they consist merely of two non-metal elements
non-conductors of electricity
e.g. H2O, CH4

Question 9

Acids

Answer 9

hydrogen containing compounds
composed of hydrogen and an anion (the hydrogen always comes first), and have no charge
H2SO4
HNO3

Question 9

Basic oxides

Answer 9

Group 1&2 form basic compounds of oxygen when they react with dioxygen
large amount of energy is released
usually ionic in nature
readily react with water except for a few exceptions (M2O3, MO2, ThO2)
Na2O + H2O → 2NaOH

Question 10

Acidic oxide

Answer 10

Non-metals react with oxygen
also called acid anhydrides
usually have a low melting and boiling point except for compounds like B2O3 and SiO2 which have high melting points and form giant molecules
SO3 + H2O → H2SO4
B2O3 + H2O → 2H3BO3

Question 11

Amphoteric oxide

Answer 11

compounds of oxygen which exhibits both acidic as well as basic characteristics
when react with acid undergo a neutralization reaction to form water and salt = basic proprty
reacts with alkali to form salt and water = acidic property

Question 12

Salts can be decomposed thermally

Answer 12

happens at lower temperatures when gaseous decomposition products appear

Question 13

Hydrides

Answer 13

hydrogen combined with another element
types: saline (ionic), metallic, and covalent
hydride is known as the negative ion of a hydrogen, H-, also called a hydride ion. Because of this negative charge, hydrides have reducing, or basic properties

Question 14

Covalent Hydrides

Answer 14

when a hydrogen atom and one or more nonmetals form compounds
occurs when hydrogen
covalently bonds to another element by sharing electron pairs
can be volatile or non-volatile

Question 15

Volatile

Answer 15

being readily able to be vaporized at low temperatures

Question 16

example of a covalent hydride

Answer 16

when hydrogen bonds with chlorine and forms hydrochloric acid

Question 17

Ionic Hydrides

Answer 17

also known as saline hydrides or pseudohalides
form between hydrogen and the most active metals, especially with the alkali and alkaline-earth metals of G1 + G2
hydrogen acts as the hydride ion
bond with metal atoms
usually binary compounds (i.e., only two elements in the compound) and are also insoluble in solutions

Question 18

Metallic Hydrides

Answer 18

also known as interstitial hydrides
Hydrogen bonds with transition metals
One interesting and unique characteristic of these hydrides is that they can be nonstoichiometric, meaning basically that the fraction of H atoms to the metals are not fixed.