Calculating Average Atomic Mass The atomic mass of an element is a weighted average of the different isotopes of a naturally occurring sample of the element.

Slides:

Advertisements

Similar presentations

Average Atomic Mass. How much does an atom weigh?  Protons & Neutrons:  1.67 X gram  Electrons:  9.10 X gram  To avoid working with.

Advertisements

AIM: HOW TO CALCULATE THE AVERAGE ATOMIC MASS? DO NOW:1. WHAT ARE THE 3 SUBATOMIC PARTICLES OF AN ATOM? LIST THE THREE SUBATOMIC PARTICLES AND THEIR CHARGE.

OF PROTONS, NEUTRONS AND ELECTRONS IN AN ATOM

Relative atomic mass Atoms are too small to be weighed individually, even with the best balance! We can, however, compare the masses of different atoms.

1 Average Atomic Mass Chemistry Notes. 2 Relative Atomic Mass  Masses of atoms expressed in grams are very small, for example: One atom of Oxygen-16.

Periodic Table of the Elements – Lesson 4

 Each element on the periodic table has an isotope.  What make an element have different isotopes?  There are 2 different isotopes of iron  Find the.

Average Atomic Mass. Average Atomic Mass – the weighted average of the masses of the isotopes of an element Every element is composed of several naturally.

Isotopes and Mass Number. Atomic Number The number of protons in each atom identifies it as an atom of a particular element Each atom has a unique number.

Atomic Mass. Isotopes Reminder Yesterday we learned that the mass of all atoms of a certain element are not always the same –Some atoms may have more.

Mass Number Atomic Number equals the # of... NUCLEUS ELECTRONS PROTONS NEUTRONS NEGATIVE CHARGE POSITIVE CHARGE NEUTRAL CHARGE ATOM.

Isotopes Atoms of the same element that different mass numbers

Unit 3: Atomic Theory & Structure Section 2 – Distinguishing Among Atoms.

Atoms – The Basics. Inside the Atom  Atoms are made up of smaller particles  These particles are found in different regions of the atom.

Number of Protons = Number of Electrons Number of Protons = Atomic Number Atomic Mass = Protons + Neutrons.

Average Atomic Mass The weighted average of the masses of all the naturally occurring isotopes of an element.

Unit 2 Review - Section 1 Atomic Structure and Mass.

Date: Objective Background Lab 8 The Atomic Mass of “Boltium”

Average Atomic Mass.

Isotopes  Atoms with the same number of protons but different numbers of neutrons  Ex) Carbon 12 vs. Carbon 14  These atoms have a different mass 

More about isotopes Atomic mass vs average atomic mass or atomic weight.

& Average Atomic Mass  Atoms with the same number of protons (they are the same element) but different number of neutrons.

Practice Quiz 1.Aluminum _____ 2.Zinc_____ 3.Bromine_____ 4.Sodium_____ 5.Flourine_____ 6.Gold_____ 7.Copper_____ 8.Nickel _____ 9. Ca __________ 10. C__________.

Unit 3: Atomic Structure Atomic Mass Units (amu) and Calculating Atomic Mass.

 Atomic Number- the number of protons in the nucleus of an atom of that element  Ex: Hydrogen atoms have only one proton in the nucleus, so the atomic.

4.7 Atomic Mass Even the largest atoms have very small masses (Fluorine – x ) Even the largest atoms have very small masses (Fluorine –

Chapter 4 Section 4.  There are about 118 known types of atoms.  Each element has it’s own type of atom.  All atoms of an element have to have one.

Using Isotope Data to Find a Weighted Average.  Each isotope will have two values associated with it.  Mass of Isotope  Percent Abundance (% found.

Atomic Mass. Masses in amu Only carbon-12 has an atomic mass exactly equal to its mass # One atomic mass unit (amu) is defined as 1/12 the mass of a carbon-12.

 The weighted average of its naturally occurring isotopes. Chemical Name Atomic # Chemical Symbol Atomic Mass (Average Atomic Mass)

Chapter 3 Average Atomic Mass. Section 3 Counting Atoms Relative Atomic Masses The standard used by scientists to compare units of atomic mass is the.

Average Atomic Mass. Relative Atomic Masses  Masses of atoms (in grams) are very small, so for convenience we use relative masses.  Carbon-12 is our.

Determining Average Atomic Mass

Average Atomic Mass.   atomic masses reported in periodic table represent: weighted average of masses of all naturally occurring isotopes of an element.

Average Atomic Mass What is average atomic mass? Average atomic mass is the weighted average of the atomic masses of the naturally occurring isotopes of.

Chemical Stoichiometry: The Mole Concept Mr. Forte Atascadero High School.

J OURNAL #21 Determine the # protons, neutrons and electrons for the following elements: Lithium Carbon-14 Iron (Fe)

Atomic Structure. I. Atoms The atom is the basic unit of matter.

Atomic Mass. Atomic mass Most of the mass of an atom is in the nucleus. Most of the mass of an atom is in the nucleus. The nucleus is where all of the.

Chapter 4 AVERAGE ATOMIC MASS. Atomic Mass… n The weighted average of the masses of all the naturally occurring isotopes of that element. n Is not a whole.

WEIGHTED AVERAGE MASS NUMBER: 1)The mass number on the periodic table is calculated from the weighted average of the most abundant isotopes. 2) Abundance.

Distinguishing Among Atoms. Objectives Define isotope and nuclide Use atomic number, mass number, and charge to determine the number of protons, neutrons,

Atomic Mass. How many isotopes? There are 81 elements with at least one stable isotopes All elements above atomic number 83 (Bi) are unstable; their isotopes.

Atomic Mass Mrs. Cook. Atomic Mass - The average relative mass of all naturally occurring isotopes of an element. relative mass – The mass of one object.

Same Element Different Atom- Isotopes All atoms of a particular element are not exactly alike. Some elements have atoms with different masses (isotopes)

Isotopes are atoms of the same element that have a different number of neutrons For example, Hydrogen has 3 isotopes: Protium (0 neutrons) Deuterium (1.

Warm-Up -Write the correct Nuclide Symbol for the following elements: *19 p+, 20 n *82 e-, 125n *Mass # 238, neutrons= 146.

Protons, Neutrons and Electrons

4.5 Isotopes and Atomic Mass

How many isotopes? There are 81 elements with at least one stable isotope; 279 stable isotopes in all. All elements above atomic number 83 (Bi) are unstable;

Unit 5 lec 2- Subatomic particles

ATOMIC STRUCTURE THE NUCLEUS: 1) THE PROTON:

Calculating Atomic Mass

Calculating Average Mass

What is average atomic mass?

What is average atomic mass?

Estimating the Mass Number:

ATOMIC STRUCTURE THE NUCLEUS: 1) THE PROTON:

Isotopes and Calculating Atomic Mass

Atomic Number and Mass Number

Atomic Structure.

0:56 0:55 0:54 0:53 0:57 0:58 1:02 1:01 1:00 0:59 0:52 0:51 0:44 0:43 0:42 0:41 0:45 0:46 0:50 0:49 0:48 0:47 1:03 1:04 1:19 1:18 1:17 1:16 1:20 1:21 1:25.

Calculating Average Atomic Mass

Aim: How to Calculate the Average Atomic Mass?

Chemistry Chapter 3 Section 3

Presentation transcript:

Calculating Average Atomic Mass The atomic mass of an element is a weighted average of the different isotopes of a naturally occurring sample of the element. WEIGHTED AVERAGE: Grades are often computed using a weighted average. Suppose that homework counts 10%, labs 20%, and tests 70%. If Pat has a homework grade of 92, a lab grade of 68, and a test grade of 81, what is his grade? (0.10)(92) + (0.20)(68) + (0.70)(81) = 79.5 We can do this for isotopes! Average Atomic Mass Fractional abundance of isotope 1 { = x Mass of isotope 1 } Fractional abundance of isotope 2 { + x Mass of isotope 2 } Quiz LabTest 29 Cu Copper Average Atomic Mass To calculate the atomic mass of an element, multiply the mass of each isotope by its natural % abundance, expressed as a decimal, and then add the products.

If you had 100 Atoms of Carbon 12 C 13 C 12 C 6 C Carbon Carbon has an average atomic mass very close to that of Carbon-12 because close to 99% of naturally occurring carbon on earth is carbon-12 and only 1% is carbon-13. Carbon-12 Carbon-13

Carbon has two stable isotopes, Carbon-12 and Carbon-13. Calculate the average atomic mass of carbon using the data below. 12 C 13 C Mass number/IsotopeExact weight (amu)Percent Abundance Carbon Carbon Average Atomic Mass Fractional abundance of isotope 1 { = x Mass of isotope 1 } Fractional abundance of isotope 2 { + x Mass of isotope 2 } ( x ) + ( x ) = amu Carbon-12Carbon-13 Fractional abundance is the percent abundance divided by 100!

Nitrogen has two stable isotopes, Nitrogen-14 and Nitrogen-15. Calculate the average atomic mass of nitrogen using the data below. 14 N 15 N Mass number/IsotopeExact weight (amu)Percent Abundance Nitrogen Nitrogen Average Atomic Mass Fractional abundance of isotope 1 { = x Mass of isotope 1 } Fractional abundance of isotope 2 { + x Mass of isotope 2 } ( x ) + ( x ) = amu Nitrogen-14Nitrogen-15 Mass number vs. exact weight/atomic mass?

% Abundanceamu Average Atomic Mass of Magnesium?

What is the Fractional Abundance of Carbon-12 ( amu) and Carbon-13 ( amu) granted that the average atomic mass of Carbon is ? (12 amu * x ) + ( amu * y) = But x + y must = 1 (must have 100%) So writing y in terms of x yields (12 amu * x ) + ( amu *(1- x)) =

Quirky Quantum Chemistry If a small marble has a mass of 3 grams and a large marble has a mass of 5 grams how much will three small marbles and two big marbles weigh in total? Well, atoms don’t follow these simple rules. Helium has two protons and two neutrons but the mass of a helium atom is actually less than the combined mass of two protons and two neutrons. AN ATOM WEIGHS LESS THAN THE SUM OF ITS PARTS! This is called a mass defect and its related to Einstein’s equation E =mc 2. Crudely: Some of the mass is converted into binding energy used to hold the nucleons together.

1.What is the difference between the mass number and the exact atomic mass? 2.An atom cannot have a fraction of a neutron or a proton. Why is the exact mass of various elements not a whole number? Hint, I am not asking about the weighted average on the periodic table? 3.The sum of its parts does not equal the whole. What does that mean in regards to an atom? 4.Boron has an atomic mass of amu according to the periodic table. However, no single atom of boron has a mass of amu. How do you explain this? 5.The average atomic mass of Copper is amu. Which of copper’s two naturally occuring isotopes is more common, Copper-63 or Copper-65? 6.Boron has two isotopes, Boron-10 and Boron-11. Which is more abundant given that the atomic mass of Boron is Calculate the atomic mass of bromine. The two isotopes of bromine have atomic masses and relative abundances of amu (50.69%) and amu (49.31%). 8.What is the % Abundance of Lithium-6 ( amu) and Lithium 7 ( amu) if the average atomic mass of lithium is % Abundanceamu 9. Calculate the average atomic mass of Calcium.