Homework Private study work bring notes to show
Homework Private study work (bring notes to show me next lesson); • Read pages 6 – 7 in your text book and complete the practice questions on each double page spread • Look at the following websites • http: //www. chemguide. co. uk/atoms/prope rties/gcse. html#top • http: //www. chemnotes. org. uk/f 321. html • Topic 1, concentrate on atomic structure
Look at the information below. What does it tell you? Write down anything you can think of. 35 Cl 17 37 Cl 17 -1 35. 5 Cl 37 Cl 17 17 24 11 +1 Na
AS Chemistry Lesson 1 atomic structure 07 March 2021
Lesson objectives Atomic Structure • (a) describe protons, neutrons and electrons in terms of relative charge and relative mass; • (b) describe the distribution of mass and charge within an atom; • (c) describe the contribution of protons and neutrons to the nucleus of an atom, in terms of atomic (proton) number and mass (nucleon) number; • (d) deduce the numbers of protons, neutrons and electrons in: – (i) an atom given its atomic and mass number, – (ii) an ion given its atomic number, mass number and ionic charge; • (e) explain the term isotopes as atoms of an element with different numbers of neutrons and different masses;
Remember this is a model. It is the nuclear model of an atom. ELECTRON – negative (-1), mass 1/2000 (so small compared to the nucleus we say it is negligible). Nucleus contains protons and neutrons Occupy shells around the nucleus + NEUTRON – neutral (0), same mass as proton (“ 1”) + - Structure of the atom PROTON – positive (+1), same mass as neutron (“ 1”) Draw a labelled diagram for the structure of the atom. This can be any atom or just a generic diagram.
Essential information Subatomic particle Relative mass Relative charge Proton 1 +1 Neutron 1 0 electron, e- 1/2000 -1
Most of the atom is empty space! If you imagine an atom being the size of Wembley stadium, the nucleus would be about the size of a football on the centre spot. The electrons would be two peas flying around the whole stadium. The rest of it: emptiness.
What is the structure of an atom? Protons, neutrons and electrons are not evenly distributed in an atom. The protons and neutrons exist in a dense core at the centre of the atom. This is called the nucleus. The electrons are spread out around the edge of the atom. They orbit the nucleus in layers called shells. In an atom the number of positive protons is the same as the number of negative electrons.
Nucleus contains protons and neutrons, overall charge is positive. Most of an atoms mass is found here. Most of the atom is empty space. Electrons give the atom it’s overall size and shape. An atom has no overall charge because the number of positive protons is the same as the number of negative electrons.
An actual AS chemistry exam question White boards
Answer
Isotopes The number of protons is what determines which element it is. 8 protons = oxygen 2 protons = helium But the number of neutrons can vary. If the neutrons vary then what else will vary? If neutrons vary then so does the atoms…. …. mass!
Isotopes Definition: • Isotopes are atoms of the same element with different numbers of neutrons. Isotopes of an element will have: • – – – • different masses the same number of protons and electrons different numbers of neutrons Isotopes of an element react in exactly the same way because reactions involve electrons, neutrons have no effect on chemical reactions.
Mass number (nucleon number) total number of protons and neutrons in the nucleus A Z X Element symbol Symbol for an isotope Atomic (proton) number 1) Number of protons in the nucleus – defines the element 2)All atoms of the same element have the same number of protons
Chlorine -35 and -37 are examples of isotopes Different mass numbers mean different numbers of neutrons 35 17 18 neutrons (35 – 17) Cl 37 17 Cl 20 neutrons (37 – 17) The atomic numbers are the same. Both isotopes have 17 electrons and 17 protons Remember Number of neutrons = mass number – atomic number
Isotopes of Carbon is a mixture of three isotopes, for each of them complete the table: Isotope Mass number Atomic Number No. of neutrons White boards 12 6 C C 13 6 14 6 C
Actual year 12 exam question White boards
Ions What is an ion? It is an atom that is charged. How does this happen? Either by gaining or losing one or more electrons. Definition An ion is a positively or negatively charged atom or (covalently bonded) group of atoms (a molecular ion)
Ions • Ions have different numbers of protons and electrons
Ions White boards Complete the table: Ion Mass number, A Atomic Number, Z No. of protons No. of neutrons No. of electrons Overall charge 23 11 Na+ 35 17 Cl-
White boards
AS exam question Complete on worksheet Q 1
More Exam Questions We will look at more exam questions for this topic. This is work that we have covered at GCSE, but it is important that we understand these topics as they are fundamental ideas in chemistry and you will constantly come back to them. Also it is good to look at exam papers. Some questions will look similar, that is because they are! This means you can easily pick up marks or lose marks if you constantly make the same mistakes. Look at past exam papers and mark schemes. Use them to help with your revision. See what the key words are that the exam board are looking for and see what the key things are that they are not looking for. Just like with GCSE they are freely available on the internet.
Complete the following exam questions on the worksheet Q 2
Q 2
Q 2 ii
Q 3
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Q 3
Q 4
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Q 6
Ionic formula
Ions questions a) How many protons, neutrons and electrons are in the following atoms and ions? b) Which are atoms and ions? How do you know? 1) 17 Li 2) 24 Na 3) 19 F 4) 55 Fe 3 11 9 26 5) 3919 K+ 6) 199 F- 7) 3920 Ca 2+ 8) 178 O 2 -
Isotope questions (actual exam ones) 1. Hydrogen, deuterium and tritium are all isotopes of each other. a) Identify one similarity and one difference between these isotopes. b) Deuterium can be written as 2 H. Determine the number of protons, neutrons and electrons in a neutral deuterium atom. c) Write a nuclear symbol for tritium, given that it has 2 neutrons. 2. A certain atom X has one less proton and two more neutrons than K. What are its atomic number and mass number? 3. Explain in terms of sub atom particles, why C-12 and C-14 are isotopes
Lesson objectives Atomic Structure • (a) describe protons, neutrons and electrons in terms of relative charge and relative mass; • (b) describe the distribution of mass and charge within an atom; • (c) describe the contribution of protons and neutrons to the nucleus of an atom, in terms of atomic (proton) number and mass (nucleon) number; • (d) deduce the numbers of protons, neutrons and electrons in: – (i) an atom given its atomic and mass number, – (ii) an ion given its atomic number, mass number and ionic charge; • (e) explain the term isotopes as atoms of an element with different numbers of neutrons and different masses;
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