We think you have liked this presentation. If you wish to download it, please recommend it to your friends in any social system. Share buttons are a little bit lower. Thank you!
Presentation is loading. Please wait.
Published byNoel Lynch
Modified over 4 years ago
1 of 26© Boardworks Ltd 2009
2 of 26© Boardworks Ltd 2009
3 of 26© Boardworks Ltd 2009 Particle electron neutron proton Relative charge Relative mass Subatomic particles Atoms are composed of three subatomic particles: protons, neutrons and electrons. The two important properties of these particles are mass and charge: 1/1840 01 +11 The mass of electrons is negligible when compared to the mass of protons and neutrons, so their mass is not included when calculating the mass of the atom.
4 of 26© Boardworks Ltd 2009 Atomic number and mass number The mass number of an atom is the number of protons plus the number of neutrons, and is represented by the symbol A. When an atom is represented by its symbol, the mass number, and sometimes the atomic number, are shown. The number of protons in an atom is known as the atomic number or proton number and is represented by the symbol Z. mass number (A) atomic number (Z)
5 of 26© Boardworks Ltd 2009 What are isotopes? atomic number is the same mass number is different The reactivity of different isotopes of an element is identical because they have the same number of electrons. Isotopes are atoms of the same element that contain different numbers of neutrons. The different masses of the atoms means that physical properties of isotopes are slightly different. carbon-12carbon-13
6 of 26© Boardworks Ltd 2009 Isotopes of chlorine About 75% of naturally-occurring chlorine is chlorine-35 ( 35 Cl) and 25% is chlorine-37 ( 37 Cl). 17 protons 18 neutrons 17 electrons 17 protons 20 neutrons 17 electrons
7 of 26© Boardworks Ltd 2009 NeutronsProtonsIsotope Isotopes of carbon There is also more than one isotope of carbon: 8 14 C 76 13 C 66 12 C All isotopes of carbon have 6 protons and so have 6 electrons. Because chemical reactivity depends on the number of electrons the reactivity of the isotopes of carbon is identical. 6
8 of 26© Boardworks Ltd 2009 What’s the number?
9 of 26© Boardworks Ltd 2009
10 of 26© Boardworks Ltd 2009 ‘Weighing’ atoms Mass spectrometry is an accurate instrumental technique used to determine the relative isotopic mass (mass of each individual isotope relative to carbon-12) and the relative abundance for each isotope. From this, the relative atomic mass of the element can be calculated. Some uses of mass spectrometry include: carbon-14 dating detecting illegal drugs forensic science space exploration.
11 of 26© Boardworks Ltd 2009 Mass spectrometry
12 of 26© Boardworks Ltd 2009 Parts of the mass spectrometer
13 of 26© Boardworks Ltd 2009 Process of mass spectrometry
14 of 26© Boardworks Ltd 2009 Mass spectra of monatomic elements
15 of 26© Boardworks Ltd 2009 Mass spectra of diatomic elements
16 of 26© Boardworks Ltd 2009 Process of mass spectrometry
17 of 26© Boardworks Ltd 2009
18 of 26© Boardworks Ltd 2009 What is relative atomic mass? The relative atomic mass (A r ) of an element is the mass of one of its atoms relative to 1/12 the mass of one atom of carbon-12. Most elements have more than one isotope. The A r of the element is the average mass of the isotopes taking into account the abundance of each isotope. This is why the A r of an element is frequently not a whole number. average mass of an atom × 12 mass of one atom of carbon-12 relative atomic mass (A r ) =
19 of 26© Boardworks Ltd 2009 Using mass spectra to calculate A r The mass spectrum of an element indicates the mass and abundance of each isotope present. For example, the mass spectrum of boron indicates two isotopes are present: How can this be used to calculate the A r of boron? 0 100 20 40 60 80 abundance (%) 024681012 m/z 10 B (20%) 11 B (80%)
20 of 26© Boardworks Ltd 2009 Calculating A r Most elements have more than one isotope. The relative atomic mass of the element is the average mass of the isotopes taking into account the abundance of each isotope. Example: what is the A r of boron? In a sample of boron, 20% of the atoms are 10 Br and 80% are 11 Br. If there are 100 atoms, then 20 atoms would be 10 Br and 80 atoms would be 11 Br. The relative atomic mass is calculated as follows: A r of Br = (20 × 10) + (80 × 11) 100 A r of Br = 10.8
21 of 26© Boardworks Ltd 2009 Calculating A r of magnesium Example: What is the A r of magnesium? In a sample of magnesium, 79.0% of the magnesium atoms are 24 Mg, 10.0% are 25 Mg and 11.0% are 26 Mg. 2. Add these values, and divide by 100 (1896 + 250 + 286) / 100 A r of Mg = 24.3 24 × 79.0 25 × 10.0 26 × 11.0 1. Calculate mass × abundance of each isotope
22 of 26© Boardworks Ltd 2009 A r calculations
23 of 26© Boardworks Ltd 2009
24 of 26© Boardworks Ltd 2009 Glossary
25 of 26© Boardworks Ltd 2009 What’s the keyword?
26 of 26© Boardworks Ltd 2009 Multiple-choice quiz
Understanding Chemical Reactions Lesson 1. Lesson Objectives Ensure familiarity with concept of atomic structure. Understand what isotopes are. Understand.
Section 4.2—Atomic Structure. What are atoms? Atom - smallest piece of matter that has the chemical properties of the element.
Atomic Structure Nucleus – contains protons and neutrons
Atomic Mass & Molar Mass
Atomic Mass & Number Isotopes The Periodic Table.
Essential Question: How do atoms of the same element differ?
Isotopes. Atomic Structure Electron configuration Summary activities Isotopes Introducing atoms Atomic number and mass number Contents.
Subatomic Particles and Isotopes. Subatomic Particles Protons- Positively Charged Protons- Positively Charged Located in the nucleus Located in the nucleus.
Boardworks AS Chemistry Atomic Structure
Chapter 4 Lecture Basic Chemistry Fourth Edition Chapter 4 Atoms and Elements 4.5 Isotopes and Atomic Mass Learning Goal Give the number of protons, electrons,
Chemical Ideas 2.1. A simple model of the atom.. What’s inside? In the nucleus? Protons And around the nucleus? Electrons Neutrons.
Chapter 4. Smallest part of an element that retains the properties of that element all elements are made of indivisible atoms.
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
Chapter: 2 Atomic Structure
Particle electron neutron proton Relative charge Relative mass Subatomic particles Atoms are composed of three subatomic particles: protons, neutrons and.
Unit 2 Review - Section 1 Atomic Structure and Mass.
1 of 7© Boardworks Ltd of 7© Boardworks Ltd 2009 Relative atomic mass The relative atomic mass (A r ) of an element is the mass of one of its.
Mass spectroscopy – learning objectives Outline the early developments in mass spectrometry. Outline the use of mass spectrometry in the determination.
Determining the NUMBER of Protons Electrons and Neutrons in Atoms, Ions, and Isotopes.
© 2019 SlidePlayer.com Inc. All rights reserved.