Chemistry Revision

Question 1

Define cation

Answer 1

“An ion with a net positive charge”
Cations have donated electrons. With more protons than electrons, these ions have an overall positive charge.

Question 2

Define an atomic number

Answer 2

“The number of protons in each atom of an element”
Each element has a unique atomic number. In neutral atoms, this is also the number of electrons.

Question 3

Define anion

Answer 3

“An ion with a net negative charge”
Anions have gained electrons. With more electrons than protons, these ions have an overall negative charge.

Question 4

What is a covalent bond?

Answer 4

“An attraction between atoms that share electrons”
Covalent bonds form when two non-metal atoms share valence electrons.

Question 5

What is a compound?

Answer 5

“A substance made up of two or more types of atom bonded together”
Water is a compound with molecules made of one oxygen atom bonded to two hydrogen atoms.

Question 6

What is a chemical bond?

Answer 6

“An attractive force that holds two atoms together”
Chemical bonds are broken or formed during chemical reactions.

Question 7

Define delocalized

Answer 7

“Able to move freely from one place to another”
The valence electrons in metals are delocalized so they can move freely between atoms.

Question 8

What is electron configuration?

Answer 8

“The arrangement of electrons in shells around an atom’s nucleus”
Nitrogen has the configuration 2.5 while magnesium has the configuration 2.8.2

Question 9

Define electron shell

Answer 9

“A grouping of electrons around the nucleus of an atom”
Electron shells increase in energy level with distance from the nucleus.

Question 10

Define a group

Answer 10

“A column in the periodic table”
Elements in the same group have the same number of valence electrons and tend to have
similar properties.

Question 11

What is an ionic bond?

Answer 11

“An electrostatic attraction between ions with opposite charges”
Ionic bonds form when metal atoms transfer electrons to non-metal atoms, forming cations and anions.

Question 12

Define an ion

Answer 12

“An atom or molecule with a net charge”
A neutral atom that gains an electron becomes a negative ion with a charge of –1.

Question 13

What is a lattice?

Answer 13

“A repeating arrangement of atoms in a solid”
Lattices are highly ordered structures held together by
bonds between atoms.

Question 14

Define metal

Answer 14

“A shiny, malleable element that conducts heat and electricity”
Metals include magnesium and calcium. They tend to form cations by losing valence electrons.

Question 15

What is a metallic bond?

Answer 15

“A strong attraction between atoms due to
delocalized electrons”
Metallic bonds form between metal cations that are surrounded by a ‘sea’ of delocalized electrons.

Question 16

What is a molecule?

Answer 16

“A group of atoms bonded together”
An oxygen gas molecule is made up of two oxygen atoms bonded together.

Question 17

Define a neutral atom

Answer 17

“An atom with no net charge”
An atom is neutral when it has an equal number of protons and electrons.

Question 18

Define noble gas

Answer 18

“An element that is nonreactive due to its full
valence shell”
The noble gases have full valence shells so they don’t tend to form chemical bonds with other atoms.

Question 19

Define period

Answer 19

“A row in the periodic table”
Elements in the same period have the same number of
electron shells.

Question 20

What is a valence electron?

Answer 20

“An electron in the outermost occupied shell of an atom”
Valence electrons can be transferred or shared with other atoms to form chemical bonds.

Question 21

What is a valence shell?

Answer 21

“The outermost occupied shell of an atom”
Atoms form bonds to obtain full valence shells. They can do this by transferring or sharing electrons.

Question 22

Define non-metal

Answer 22

“A dull, brittle element that does not conduct heat or electricity”
Non-metals include sulfur and oxygen. They tend to form anions by gaining valence electrons.

Question 23

What is the periodic table?

Answer 23

“An arrangement of all chemical elements organized by their atomic number”