# An ion with 17 protons, 20 neutrons, and 18 electrons has a mass number of?

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17 protons and 20 neutrons add up to a molecular mass of 37, the electron mass is inconsequential.

• 4 years ago

If you do some basic research or look up wikipedia you will find that ordinary Hydrogen 1H has one proton and one electron, Deuterium 2H has one proton, one neutron and one electron since you have the masses of the individual nuclides you can add them up and do the math. 2. they all have 17 protons so find the atomic number 17 on the periodic table. Both a and b have an extra neutron so they will be an Isotope so the atomic mass will be 17+18=35 and c has 3 extra neutrons so the mass no is 37. a. has lost one electron so it is an ion with a charge of +, b. has equal nos of p and e so it is neutral. and c. has gained one electron so it will have a charge of -. The symbol is superscript mass Name of the element superscript charge eg. for carbon 14 ion 14C- (14 and - should be superscript) I am not sure if you have read your texts. I would encourage you to read basic atomic chemistry and seek help from your tutor

• Norrie
Lv 7

Electrons are not included in the mass number. Only Protons and Neutrons.

17 Protons and 20 Neutrons = an Atomic Mass Number of 37.

(A Stable Isotope of a Chlorine ion Cl(-1). Look it up if you must.

(In this case, although electrons are not considered in the Atomic Mass, the fact that it's an ion with 18 electrons makes it a negative particle. The only other substance with 18 electrons is the Noble gas Argon but, that also has 18 Protons and 22 neutrons).

Normal, Neutral chlorine has 17 electrons, 17 Protons and 18 Neutrons).

Stick your thumb where it will do more good....!!!

COMPOSITION OF POLLUTION - FREE GROUND LEVEL AIR

Nitrogen

78.08%

Oxygen

20.95%

Carbon Dioxide

0.03%

COMPOSITION OF UNIVERSE

COMPOSITION OF EARTH

Hydrogen

60.40%

Iron

35.4%

Helium

36.56%

Oxygen

27.8%

Oxygen

0.96%

Magnesium

17.0%

Carbon

0.30%

Silicon

12.6%

ELEMENTS

90 Naturally occurring

19 Synthesized

109 TOTAL

ATOM Chapter 3

What is it?

Def: The smallest particle still having the characteristics of an element. It is made up of smaller particles: electrons, protons, and neutrons.

Simplest atom is H (hydrogen).

electron

proton

PROTON

1. Positive charge

2. "Weighs" 1 amu (atomic mass unit)

1 lb. = 273 x 1024 amu

3. The number of protons is the atomic number of an element.

4. The number of protons tells you what the element is.

5. What element has 6 protons?

6. How many protons in the element nitrogen (N)?

ELECTRON

1. Negative charge

2. 1835 electrons weigh 1 amu.

3. Responsible for chemical bonds

NEUTRON

1. No net charge

2. Weighs 1 amu

ATOMIC WEIGHTS

To get the atomic weight you add the number of protons and neutrons. When the protons and neutrons are considered as a unit, they are referred to as "nucleons".

Def. Average weight of all the atoms of an element.

Hydrogen has 1 proton and 1 electron, totaling 1 amu.

Deuterium has 1 proton (1 amu), 1 neutron (1 amu),

and 1 electron, totaling 2 amu.

Tritium has 1 proton (1 amu), 2 neutrons (2 amu), and 1 electron, totaling 3 amu.

ISOTOPES

Def: Atoms of the same element that have the same

atomic number but have different mass numbers.

The isotopes of an element all have the same number of protons but a different number of neutrons.

Hydrogen, deuterium and tritium are isotopes.

ISOTOPES OF URANIUM

238 235

U U

92 92

What does the 92 mean? What does the 238 mean?

Summary:

Atomic number

Atomic weights

ISOTOPES

A

X X = symbol of the element

Z Z = number of protons

A = mass number (number of protons and neutrons)

1H = hydrogen 2H = deuterium 3H = tritium

1 1 1

ATOMIC STRUCTURE

2 electrons can fit on the first level

8 electrons on the second

Atoms are happy when a shell or level is complete - will enter into reaction just to get the number of electrons for that shell.

IONS

When an atom does not have the same number of electrons and protons, it has a charge. This is an ion.

If an ion had 11 protons and 10 electrons, it would be a positive ion. These are called cations.

What element has 11 protons?

If an ion had 17 protons and 18 electrons, it would be a negative ion. These are called anions.

What element has 17 protons?

Atoms and Ions

Atoms have no net charge. They are neutral.

Ions have a charge, either positive or negative.

A positive ion has more protons than electrons. CATION

A negative ion has more electrons than protons. ANION

The ion of an atom has very different chemical properties than the atom or molecule. Sodium is a soft metal, which reacts with water and gives explosive hydrogen.

The sodium ion is half of table salt NaCl, which dissolves in water and is needed for human life.

23Na 23Na+

# protons

# neutrons

# electrons

Problems

Chemical Symbol

#Protons

# Neutrons

#Electrons

Charge

Name

4020Ca++

19078Pt

22387Fr

12953I-

4He

7

6

Carbon

14

15

0

18

18

Sulfur ion

30

24

Iron ion

118

+3

Gold ion

9

9

-1

mass number is the same as amount of protons plus amount of neutrons.

so, the mass must be 17 + 20 = 37

Although amount of protons isn't equal with electron, it only causes to be negative charge of atoms (ion)

37

• Anonymous