Week 3 Module 4 - Ions

A Negative Ion = Anion

A Negative Ion = Anion

True

A plus sign (+) tells us that electrons are lost and a minus sign tells us that electrons are gained. The number next to the plus or minus sign tells us how many electrons are lost or gained. The number "1" is not written only the plus or minus sign in that case.

Lithium Ion

A) it is a lithium ion(Li+). Li will lose an electron so that it is stable with a complete first shell and it will lose the shell in which the 3rd electron had been.

they have an equal number of positively charged protons and negatively charged electrons which allows their charges to cancel out.

Atoms are neutral because:

ANIONS

Atoms that have gained electrons become negatively charged IONS. Negatively charged ions are called _____________.

CATIONS

Atoms that have lost electrons become positively charged IONS. Positively charged ions are called __________.

Protons= 20 Electrons= 20 Neutrons= 20 (atomic mass 40- atomic number 20)

Ca (calcium atom). Atomic number = 20, Atomic mass= 40 Protons= Electrons = Neutrons =

1) There is a plus sign so electrons have been lost. 2) There is a 2 next to the sign indicating that 2 electrons have been lost

Ca2+

Protons= 20 Electrons = 18 ( the reason for this is because a 2+ charge on the ion tells us that 2 electrons were lost so we subtract 2 from our usual number of electrons. 20(usual number)- 2(number lost)= 18 Neutrons = 20 (atomic mass 40 - atomic number 20)

Ca2+ (calcium ion). Atomic number =20, Atomic mass=40 Protons= Electrons = Neutrons =

number of protons: 11 number of electrons: 10 number of neutrons: 12

Calculate for Na+. (Atomic number = 11, Atomic mass= 23) number of protons: number of electrons: number of neutrons:

Nonmetal example

Chlorine (Cl) has 7 electrons in its outermost shell, it needs 8 to complete the octet. Chlorine, therefore, will gain an electron in order to do so. It would take a lot of energy to lose 7 electrons so energy-wise it is more efficient to gain the additional election needed to complete the shell to form the chloride ion (Cl-).

Protons= 9 Electrons= 9 Neutrons= 10 (atomic mass 19 -atomic number 9)

F (fluorine atom). Atomic number = 9, Atomic mass= 19 Protons= Electrons = Neutrons =

1) There is a minus sign indicating electrons have been gained. 2) There is no number written next to the sign so we know 1 electron has been gained.

F-

Protons= 9 Electrons= 10 ( a minus sign tells us that electrons have been gained so we add an electron to our usual number, 9+1=10) Neutrons= 10 (atomic mass 19 -atomic number 9)

F- (fluoride, a fluorine ion) Protons= Electrons = Neutrons =

3

For Al3+ how many electrons have been gained or lost?

in the presence of a charge

How do atoms and ions differ?

True

IONS ARE DIFFERENT THAN ATOMS (T/F)

True

IONS carry a charge. Atoms are neutral, they have a charge of 0. (T/F)

proton number and electron number are no longer equal.

Ions carry a charge because:

1) There is a plus sign this means electrons have been lost. 2) no number is written so this means 1 electron has been lo gained or lost is 1 it will not be written in

Li+

True

Metals form cations. T/F

1) There is a minus sign indicating electrons have been gained. 2) There is a 2 next to the minus sign indicating that 2 electrons have been gained.

O2-

Lithium Atom

We see that an Li atom has a complete first shell because it has the 2 electrons required to fill the first shell. Li only has 1 electron the second shell when it should have 8 to complete that shell. It would take tons of energy to gain 7 electrons to get 8 but it requires much less energy to lose 1 electron.

IONS

When an atom gains or loses an electron, it no longer has equal numbers of protons and electrons and it takes on an electrical charge. These charged particles are called _________.

Nonmetals

_________ produce negative ions (anions) because they have a negative valence number and gain electrons.

Metals

_________ produce positive ions (cations) because they have positive valence numbers and lose electrons.