Atomic Structure

What is the atomic mass of Lithium if 7.42% exists as lithium-6 and 92.58% exists as lithium- 7?

amu= 6.926

Magnesium has three naturally occurring isotopes. 78.70% of Magnesium atoms exist as Magnesium-24, 10.03% exist as Magnesium-25 and 11.17% exist as Magnesium-26. What is the atomic mass of Magnesium?

amu= 24.2997

Neon has two major isotopes, Neon-20 and Neon-22. Out of every 250 neon atoms, 225 will be Neon-20, and 25 will be Neon-22. What is the atomic mass of Neon?

amu= 20.2

Natural samples of copper contain two isotopes. Copper- 63 has a mass of

62.930 amu and Copper- 65 has a mass of 64.928 amu. The percent abundance of

Copper-63 is 69.09%. Calculate the atomic mass of copper.

63.55 amu

Calculate the atomic mass of an element if 60.4% of the atoms have a mass of 68.9257 amu and the rest have a mass of 70.9249 amu. Identify the element in the periodic table.

69.7 amu, Gallium

Copper metal is well-known since the dawn of civilization that has two isotopes, Cu-63 and Cu-65 that have atomic masses of 62.93 amu and 64.828 amu respectively. Their percent abundances are respectively 69.09 % and 30.91 %. Determine the average atomic mass of copper.

63.55 amu

If the atomic mass of hydrogen is 1.001, explain the percent abundance of the hydrogen- 1 and hydrogen- 2 isotopes.

hydrogen- 1 is the most abundant

Estimate the percent abundances for the following isotopes of phosphorus: phosphorus- 31, phosphorus- 29.

phospohorus-31 would be much more abundant than phosphorus- 29

Calculate the atomic mass of bromine. The two isotopes of bromine have atomic masses and relative abundance of 79.92 amu (50.69%) and 80.92 amu (49.31%).

79.90 amu

Boron- 11 has two isotopes: boron- 10 and boron-11. Which is more abundant, given that the atomic mass of boron is 10.81 amu.

boron- 11

average atomic mass formula method 1

(Percent to decimal)(mass) + (percent to decimal)(mass)

Any naturally occurring element is actually made up of various isotopes in a ________ __________ _________.

constant percentage abundance

Practice Problem: Method 1

There are five (5) naturally occurring isotopes of nickel:

Isotope Mass (amu) Relative Abundance (%) nickel-58: 57.9353 67.84

nickel-60: 58.9332 26.23

nickel-61: 60.9310 1.19

nickel-62: 61.9283 3.66

nickel-64: 63.9280 1.08

Calculate the average atomic mass of nickel:

(57.9353 x 0.6784) + (58.9332 x 0.2623) + (60.9310 x 0.0119) + (61.9283 x 0.0366) + (63.9280 x 0.0108) = 58.4436 AMU

average atomic mass formula method 2

(mass)(%)+(mass)(%)/100

Average Atomic Mass: method 2

Isotopic Mass (AMU) Relative Abundance (%)

Iodine 127 80%

Iodine 126 17%

Iodine 128 3%

(127 x 80) + (126 x 17) + (128 x 3)

100

= 126.86 AMU

20

Number of protons in calcium

Rb

Element symbol for rubidium

Cesium

Element Name for Cs

12

Number of neutrons in magnesium with a mass number of 24

22

Atomic number of titanium (Ti)

38

Number of electrons in Sr

54.94

Atomic Mass of Mn

35

Number of neutrons in Zn with a mass number of 65

126.09

Atomic Mass of iodine

54

Number of Protons in xenon (Xe)

36

Number of electrons in a krypton (Kr) atom

Gold

Element name for Au

Ag

Element Symbol for silver

146

Neutrons in uranium (U)

Radium

Element Name for Ra

Radon

Element Name for Rn

43

Number of Electrons in a Tc atom

190

Mass number osmium (Os) with 114 neutrons

80

Number of Protons for Mercury (Hg)

Indium

Element Name for In

68

Number of neutrons for Antimony (Sb) with a mass number of 119

122

Number of neutrons in Hg with a mass number of 202

75

Number of electrons in a Re atom

Iron

Element name of Fe

42

Arsenic (As) with a mass number of 75 has _________ neutrons

144

Radon- 230 has _______ neutrons

Isotope

Same element with different number of Neutrons and Mass Number

238

In Uranium-238, the mass number is _____.

protons and neutrons

The nucleus of an atom contains

electrons

Negatively charged particles that are around the nuclues

8

Carbon-14 has _____ neutrons

Atomic Mass

The average mass of all the isotopes of an element

Atom

Basic unit of matter

137.33

Atomic Mass of Barium

Palladium

I have 46 Protons

Mass Number

the sum of the number of neutrons and protons in an atomic nucleus

Positive

charge of a proton

Negative

Charge of an electron

Neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

Neutral

Charge of a neutron

Proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

location of protons

nucleus

charge of protons

positive

mass of protons in amu's

1 amu

location of neutrons

nucleus

charge of neutrons

neutral

mass of neutrons in amu's

1 amu

location of electrons

outside the nucleus, in the electron cloud/shell

charge of electrons

negative

mass of electrons in amu

0 amu (1/1870 of a proton or neutron - so negligible that we don't include it when calculating atomic mass)

what is represented by atomic number

number of protons

Number of protons in an argon atom

18

Number of electrons in an argon atom

18

Number of neutrons in an argon atom with a mass number of 42

24

Number of protons in a fluorine atom

9

Number of neutrons in a fluorine atom with 18 neutrons

9

Number of electrons in a fluorine atom

9

Which element of the periodic table has an atomic number of 6?

carbon

Which element of the periodic table contains 11 protons?

sodium

Which element of the periodic table contains 17 electrons when neutral?

chlorine

Building blocks of matter

elements

Protons have a _______ charge.

positive

Neutrons have a ________ charge.

neutral

Electrons have a ________ charge.

negative

The smallest unit of an element is called

atom

What particles are located inside the nucleus (nucleons)?

protons and neutrons

Where is the negative particles located

(outside the nucleus) electron shell/energy level

The atomic number is the same as the number of

protons

To like charges, for example positive and positive,

Repel

A positive and a negative charge

Attract

Write the complete chemical symbol for the particle with 11 protons, 12 neutrons, 11 electrons.

²²₁₁Na

Write the complete chemical symbol for the particle with 55 protons, 78 neutrons, 55 electrons.

¹³³₅₅Cs

Write the complete chemical symbol for the particle with 55 protons, 78 neutrons, 54 electrons.

¹³²₅₅Cs⁺¹

Write the complete chemical symbol for the particle with 7 protons, 7 neutrons, 10 electrons.

¹⁴₇N⁻³

Write the complete chemical symbol for the particle with 47 protons, 68 neutrons, 47 electrons.

¹¹⁵₄₇Ag

Write the complete chemical symbol for the particle with 32 protons, 36 neutrons, 32 electrons.

⁶⁸₃₂Ge

Write the complete chemical symbol for the particle with 17 protons, 19 neutrons, 17 electrons.

³⁶₁₇Cl

Write the complete chemical symbol for the particle with 17 protons, 19 neutrons, 18 electrons.

³⁶₁₇Cl⁻

Write the complete chemical symbol for the particle with 24 protons, 29 neutrons, 22 electrons.

⁵³₂₄Cr⁺²

Write the complete chemical symbol for the particle with 24 protons, 29 neutrons, 24 electrons.

⁵³₂₄Cr

Write the complete chemical symbol for the particle with 37 protons, 51 neutrons, 37 electrons.

⁸⁸₃₇Rb

Write the complete chemical symbol for the particle with 92 protons, 148 neutrons, 92 electrons.

²⁴⁰₉₂U

Write the complete chemical symbol for the particle with 78 protons, 118 neutrons, 78 electrons.

¹⁹⁶₇₈Pt

Write the chemical symbol for the particle with 78 protons, 72 electrons.

Pt⁶⁺

Write the chemical symbol for the particle with 54 protons, 54 electrons.

Xe