All in one - S2

Negative ions are called ​ (a)   . Positive ions are called ​ (b)   ​ .

• anions
• cations
• electrons
• protons
• negations
• positivions

Potassium is in the first group. In order to be stable it has to:

• Gain 7 valence electrons

• Lose 7 valence electrons

• Gain 1 valence electron

• Lose 1 valence electron

Answer explanation

Potassium is in the 1st group so it has 1 valence electron. It needs 8 valence electrons to be stable. It has ways to do it: 1. Lose its valence electron or 2. Gain 7 valence electrons. Nature will take the easiest way, meaning losing the valence electron.

An atom has to gain 2 valence electrons to be stable. Its ion is:

• A cation

• An anion

• We cannot know

Answer explanation

An atom always has the same number of protons and electrons. If it gains 2 valence electrons, it has more negative charges than positive charges. Therefore, it is an anion.

• An anion

• A cation

• We cannot know

Answer explanation

The sign as superscript shows the charge of the ion. Here, it is a negative sign so it is an anion.

The ion for aluminum is

Answer explanation

It has to lose 3 valence electrons to be stable so its charge is 3+

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

​ (a)   : Ionic compounds

​ (b)   : covalent compound

• Metal + Nonmetal
• Nonmetal + Nonmetal
• Metal + Metal
• Metaloid + Metal
• Metalloid + Metal
• Metalloid + Metalloid

Chemical bonds help to

• Decrease the potential energy

• Increase the stability

• To save valence electrons

• Increase the potential energy

• Decrease the stability

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

Covalent bonds are made by

• Sharing valence electrons

• Transferring valence electrons

• Losing valence electrons

• Creating valence electrons

Answer explanation

Ionic bonds are made with transfer of valence electrons. Never we have creation of valence electrons.

Tags

NGSS.HS-PS1-1

KF is ​ (a)  

CO is ​ (b)  

BeO is ​ (c)  

NO is ​ (d)  

• an ionic compound
• a covalent compound

Answer explanation

To know if you have an ionic compound or a covalent compound, you need to check if one of the elements in the chemical formula of the compound is in the colored area in the picture. If yes, you have an ionic compound.

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-2

NGSS.MS-PS1-5

• BeN

Answer explanation

To be stable, the ionic compound should not have charge. The only solution that works is 3 Be + 2 N.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2