Structure of the Atom â Atomic Facts
Ch 03 notes
Structure of the atom
• protons – positive charge • makes the atom unique • neutrons –neutral, no charge • this number can change—still have same element “isotope”
Periodic Table atomic number - the number of PROTONS in the nucleus Average atomic weight - a weighted average of all the masses of the naturally occurring isotopes, expressed in atomic mass units.
o Because atoms are so small we use an atomic mass unit(u) = to find the mass of one atom
1 amu = 1.66 X
10-24 g
6
C Carbon 12.0107
Atomic Facts 8
15.999
O Oxygen
Oxygen-16
o Mass number – number of protons + neutrons in the nucleus---whole number o IF NOT GIVEN: Round average atomic mass to nearest whole number. Mass number – atomic number = neutrons • The number of protons = the number of electrons– atoms are electrically neutral
Isotopes • Isotope- atoms of the same element with a different number of neutrons.
Isotopes have a different mass number but identical atomic number Mass number- number of protons and neutrons in the nucleus of an
isotope Hydrogen-1, Hydrogen-2, Hydrogen-3
• The MOST COMMON isotope is represented on the PTE!!! • https://www.youtube.com/watch?v=GsJPxR6IfZI • https://www.youtube.com/watch?v=xjY5p-1CDr8
35
79.904
17
35.453
Br
Cl
Bromine
Chlorine
Isotopes of Chlorine: Chlorine-35 and Clorine-37 Isotopes of Bromine: Bromine-79 and Bromine-81 https://www.youtube.com/watch?v=pV822HfqT44
Average Atomic Mass Average atomic mass - a weighted average of all the masses of the naturally occurring isotopes, expressed in atomic mass units. What you need to calculate the average atomic mass: Percent (%) abundance of each isotope in decimal form Mass of each isotope of the element( in amu’s)
How to calculate the weighted average: (mass isotope 1) • (percent abundance in decimal form)=
(mass isotope 2) •( percent abundance in decimal form)= (mass isotope 3)• ( percent abundance in decimal form)=
Calculate the Average Atomic Mass • A certain element is a soft, silvery-white metal that has two common isotopes, the first isotope has a mass of 85.0 amu’s the second isotope has a mass of 87.0 amu’s . If the abundance the first isotope is 72.2% and the abundance of the second isotope is 27.8%, what is the average atomic mass of this element? What is the element?
Calculate the Average Atomic Mass • There are two naturally occurring isotopes of a certain element that is used in swimming pools. The first isotope has a mass of 34.969 amu and is 75.53 % abundant in nature.The second isotope has a mass of 36.966 amu and is 24.47% abundant in nature. Calculate the average atomic mass and determine the element.
Calculate the Average Atomic Mass Mass of Isotope
Abundance
24.0 amu
78.70%
25.0 amu
10.13%
26.0 amu
11.17%
Calculate the average atomic mass. What element is this?
Structure of the atom
• protons – positive charge • makes the atom unique • neutrons –neutral, no charge • this number can change—still have same element “isotope”
Periodic Table atomic number - the number of PROTONS in the nucleus Average atomic weight - a weighted average of all the masses of the naturally occurring isotopes, expressed in atomic mass units.
o Because atoms are so small we use an atomic mass unit(u) = to find the mass of one atom
1 amu = 1.66 X
10-24 g
6
C Carbon 12.0107
Atomic Facts 8
15.999
O Oxygen
Oxygen-16
o Mass number – number of protons + neutrons in the nucleus---whole number o IF NOT GIVEN: Round average atomic mass to nearest whole number. Mass number – atomic number = neutrons • The number of protons = the number of electrons– atoms are electrically neutral
Isotopes • Isotope- atoms of the same element with a different number of neutrons.
Isotopes have a different mass number but identical atomic number Mass number- number of protons and neutrons in the nucleus of an
isotope Hydrogen-1, Hydrogen-2, Hydrogen-3
• The MOST COMMON isotope is represented on the PTE!!! • https://www.youtube.com/watch?v=GsJPxR6IfZI • https://www.youtube.com/watch?v=xjY5p-1CDr8
35
79.904
17
35.453
Br
Cl
Bromine
Chlorine
Isotopes of Chlorine: Chlorine-35 and Clorine-37 Isotopes of Bromine: Bromine-79 and Bromine-81 https://www.youtube.com/watch?v=pV822HfqT44
Average Atomic Mass Average atomic mass - a weighted average of all the masses of the naturally occurring isotopes, expressed in atomic mass units. What you need to calculate the average atomic mass: Percent (%) abundance of each isotope in decimal form Mass of each isotope of the element( in amu’s)
How to calculate the weighted average: (mass isotope 1) • (percent abundance in decimal form)=
(mass isotope 2) •( percent abundance in decimal form)= (mass isotope 3)• ( percent abundance in decimal form)=
Calculate the Average Atomic Mass • A certain element is a soft, silvery-white metal that has two common isotopes, the first isotope has a mass of 85.0 amu’s the second isotope has a mass of 87.0 amu’s . If the abundance the first isotope is 72.2% and the abundance of the second isotope is 27.8%, what is the average atomic mass of this element? What is the element?
Calculate the Average Atomic Mass • There are two naturally occurring isotopes of a certain element that is used in swimming pools. The first isotope has a mass of 34.969 amu and is 75.53 % abundant in nature.The second isotope has a mass of 36.966 amu and is 24.47% abundant in nature. Calculate the average atomic mass and determine the element.
Calculate the Average Atomic Mass Mass of Isotope
Abundance
24.0 amu
78.70%
25.0 amu
10.13%
26.0 amu
11.17%
Calculate the average atomic mass. What element is this?
