Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
L C3 Atomic Structure & the Periodic table Get your periodic tables out! Elements song! http://www.privatehand.com/flash/elements.html
Groups & periods (rows) The Periodic Table The Periodic Table
These atoms are ALL iron – there’s nothing else in here If a substance is made up of only one type of atom we say it is an element. For example, consider a tripod made up of iron
C3/3.3 Learning Objectives • Describe the structure of an atom in terms of electrons and a nucleus containing protons & neutrons. • State the relative charges & approximate relative masses of protons, neutrons and electrons. • Define proton number & nucleon number. • Use proton number and the structure of an atom to explain the basis of the periodic table with reference to first 20 elements • Define Isotopes.
Learning Objectives • Describe the build-up of electrons in ‘shells’ and understand the significance of the noble gas electronic structures and of valency electrons.
1) Atoms! Atoms are the basic building blocks of matter that make up everyday objects. People thought that atoms were the smallest particles and could not be broken into anything smaller. proton neutron electron What can you say about the size of the electron compared to the neutron & proton
What do you know… • Form a giant atom. • Atoms consist of protons, neutrons & electrons-form a giant atom as a class or as groups
What is the structure of an atom? Protons, neutrons and electrons are not evenly distributed in an atom. Pea in a football pitch 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.
Mass and electrical charge There are two properties of protons, neutrons and electrons that are especially important: • mass • electrical charge. Particle Mass Charge proton 1 +1 neutron 1 0 electron almost 0 -1
2) Atomic Number & Mass Number (Nucleon number) Mass Number- The larger number. Mass number= number of protons + number of neutrons Atomic Number/ Proton Number- Number of protons equals number of electrons. What is sodium’s atomic number? How many protons does it have? How many electrons does it have? What is its Mass Number? How many neutrons does it have? number of neutrons = mass number - number of protons = mass number - atomic number =23 – 11 =12 Neutrons
Periodic table • Elements in the periodic table are arranged in order of atomic number!
1 proton 0 neutrons 1 electron Mini-WhiteboardsHydrogen
Fluorine 9 Protons 10 Neutrons 9 Electrons
Magnesium 12 Protons 12 Neutrons 12 Electrons
Carbon 6 Protons 6 Neutrons 6 Electrons
Oxygen 8 Protons 8 Neutrons 8 Electrons
Iron 26 Protons 30 Neutrons 26 Electrons
Tin 50 Protons 69 Neutrons 50 Protons
Equal numbers of protons and electrons Atoms of elements have no charge, they are neutral. What is the charge on a fluorine atom? 19 F 9 charge = +9 charge = - 9 charge = 0 9 protons 9 electrons 10 neutrons Total charge = 0 How are the number of electrons and atomic number related in a neutral atom? They are the same.
Isotopes • Different forms of the same atoms can exist. • These are called Isotopes • Isotopes are different forms of the same element that have the sameatomic number but different mass numbers.
Notice that the mass number is different. How many neutrons does each isotope have? 16 O 17 18 O O 8 8 8 Each isotope has 8 protons – if it didn’t then it just wouldn’t be oxygen any more. Isotopes An isotope is an atom with a different number of neutrons:
Progress check • Name the sub-atomic particles within an atom. (3) • Explain why atoms are overall neutral in charge. (2) • Complete the missing numbers (11)
Self assessed answers 1)Protons, neutrons & electrons. 2)Atoms are neutral as protons (positive charge) are equal to the number of electrons (negative charges) 3) Boron-5,11 Potassium 19,20 Chromium 24,52 Mercury 80,80 Argon 18,22,18
36 3 2 211 H H Cl At 17 1 1 85 Question 4: Identifying Isotopes 4a) What is an isotope? 4b)Identify the isotopes from data about the number of electrons, protons and neutrons: • 1 proton, 1 electron, 2 neutrons • 1 proton, 1 electron, 1 neutron • 17 protons, 17 electrons, 19 neutrons • 85 protons, 85 electrons, 126 neutrons
3) Electrons • The protons & Neutrons are found in the............ • Electrons have a special home of their own. Electrons are found on ENERGY LEVELS also known as Shells! These energy levels can only house a certain number of electrons.
Electron Shells Electrons will fill the shells nearest the nucleus first. 1st shell holdsa maximum of2 electrons 2nd shell holdsa maximum of8 electrons 3rd shell holdsa maximum of8 electrons This electron arrangement is written as 2,8,8. What if you have more than 18 electrons..where does the extra electron go?...
Tasks • Mats & Play Dough • Take a tub between 3 and use this to represent your electrons. • Complete the electron arrangement for the following: F, Mg, Si, Extension: (Ar, Ca)
Electron arrangement • Electron configuration for first 20 elements. • Draw and write it down, eg, 2,8,1
Answers • Q1-All have 1 outer electron. • Q2-Both have 7 electrons in their outer shell • Q3-The group number tells us the number of outer electrons. • Q4-Group 8 Noble gases-unreactive • Q5-Iodine-7 • Arsenic-5 • Barium-2 • Q6-First electron furthest away easiest to remove. Greater distance between electrons and nucleus. • Next eight increasingly harder to remove. • Next 2 closest to shell-hardest-greater nucleus attraction-shorter distance from nucleus to electrons.
Giant atom • Form a giant atom using what you have learnt today.
Exam quest Questions- linked to learning objectives
Learning objectives-linked to exam quest • (D) Describe the structure of the atom in terms of protons, neutrons and electrons. Question 1 • (C) Identify symbols and atomic numbers using a Periodic Table. (C) State that elements are arranged in ascending atomic number. Question 2& 3 • (B) Identify the group of an element from its outer electrons and row from it shells. Question 4 • (B) Deduce the number of protons, neutrons and electrons in a particle and identify isotopes. Question 5 • (B) Deduce the electronic structure of the first 20 elements. Question 6 • (A) Explain why an atom has a neutral charge. Question 7 if you can answer WHY? To part 7bii-even better!
Giant atom • Form a giant atom using what you have learnt today.
Summary: the atom so far The nucleus is: • Made up of protons and neutrons • Positively charged because of the protons • Dense – it contains nearly all the mass of the atom in a tiny space. Electrons are: • Very small and light, and negatively charged • Able to be lost or gained in chemical reactions • Found thinly spread around the outside of the nucleus, orbiting in layers called shells.