Presentation on theme: "Topic 1 – Atomic Structure and the Periodic Table Revision Checklist"— Presentation transcript:
1Topic 1 – Atomic Structure and the Periodic Table Revision Checklist SubtopicClass NotesRevision NotesPast Exam QuestionsC2.1 MendeleevC2.2 Structure of an atomC2.3 The modern periodic tableC2.4 Electron shells
2The history of the periodic table C2.1 MendeleevThe history of the periodic table1798:Lavoisier began to divide the elements into metals and non-metals.1860:63 elements were known. John Newlands noticed that when the elements were put in order of atomic mass, that every eighth element had similar properties. But this only worked as far as calcium
31871: Mendeleev C2.1 Mendeleev Mendeleev arranged the elements in order of atomic massHe arranged the elements so that elements with similar properties were in the same vertical columns (groups).He thought there must still be some elements to discover so left gaps for them.He used the gaps to predict the properties of the undiscovered elements. For example he predicted the properties of Eka Aluminium (what we now know as Gallium)
4C2.2 Structure of an atomElementsDefinition…Element: A element is made up of only one type one atom. It cannot be spilt into simpler substancesThese atoms are ALL iron – there’s nothing else in here
5Boardworks GCSE Additional Science: Physics Radioactive Decay C2.2 Structure of an atomAtomic StructureIdeas about atomic structure have changed over time.In 1803, John Dalton said atoms were solid spheres of matter that could not be split.Dalton also suggested that each element contained identical atoms.
6Boardworks GCSE Additional Science: Physics Radioactive Decay C2.2 Structure of an atomIn 1897, whilst studying cathode rays, JJ Thomson discovered tiny particles with a negative charge.His discovery did not fit with Dalton’s model of the atom.Photo credit: The Cavendish Laboratory, University of CambridgenucleusErnest Rutherford suggested that an atom is mostly empty space with its positive charge and most of its mass in a tiny central nucleus.Electrons orbited this nucleus at a distance, like planets around the Sun.electrons
7Atomic Structure nucleus electron neutron proton C2.2 Structure of an atomAtomic Structurenucleuselectronprotonneutron
8C2.2 Structure of an atomThere are two properties of subatomic particles that are especially important:1. Mass2. Electrical charge1+11almost 0-1The atoms of an element contain equal numbers of protons and electrons and so have no overall charge.
9C2.3 The modern periodic table How many protons?The atoms of any particular element always contain the same number of protons. For example:hydrogen atoms always contain 1 proton;carbon atoms always contain 6 protons;magnesium atoms always contain 12 protons,The number of protons in an atom is known as its atomic number or proton number.It is the smaller of the two numbers shown in most periodic tables.
10C2.3 The modern periodic table Mass numberElectrons have a mass of almost zero, which means that the mass of each atom results almost entirely from the number of protons and neutrons in the nucleus.The sum of the protons and neutrons in an atom’s nucleus is the mass number. It is the larger of the two numbers shown in most periodic tables.11347131427
11Relative Atomic Mass The actual mass of a hydrogen atom is 1.7x10-24g C2.3 The modern periodic tableRelative Atomic MassThe actual mass of a hydrogen atom is 1.7x10-24g(that’s g!)Far too small a number to easily get your head around…So – we use Relative Atomic Mass instead (Ar)We compare the mass of each element to carbon-12Carbon 12 has 6 protons and 6 neutrons so we say its Ar = 12Magnesium has the same mass as 2 carbon atoms so we say its Ar = 24
12Why does chlorine have an Ar of 35.5? C2.3 The modern periodic tableWhy does chlorine have an Ar of 35.5?…because there are different isotopes of chlorine
13Isotopes always have the same atomic number, but different mass number C2.3 The modern periodic table…have the same number of protons and electrons, but different numbers of neutrons.E.g. hydrogen has 3 isotopes…IsotopesH123HydrogenDeuteriumTritiumIsotopes always have the same atomic number, but different mass number
14C2.3 The modern periodic table Chlorine always has 17 protons, but some have 18 neutrons, others have 20 neutronsIsotopesThe relative abundance (proportion) of Chlorine-35 is 75%The relative abundance (proportion) of Chlorine-37 is 25%We can use the Ar and relative abundance of the isotopes to work out the Ar of the element.
15Q1: Calculate the Ar of Neon C2.3 The modern periodic tableExample:IsotopesThe relative abundance (proportion) of Chlorine-35 is 75%The relative abundance (proportion) of Chlorine-37 is 25%Q1: Calculate the Ar of Neon
16Q1: Calculate the Ar of Neon C2.3 The modern periodic tableQ1: Calculate the Ar of NeonQ2: Calculate the Ar of LithiumQ3: Calculate the Ar of IronQ4: Calculate the Ar of SiliconQ5: Calculate the Ar of MercuryThe table shows the natural relative abundance of the main isotopes of mercury, Hg.Mass number% Relative abundance
17The Modern Periodic Table C2.3 The modern periodic tableThe Modern Periodic TableElements are arranged in order or increasing atomic number (number of protons)Horizontal rows are called periodsVertical rows are called groups (the period number tells you the number of electron shells)Elements in the same group have similar properties (because they have the same number of outer electrons)Most elements are metals (in yellow on the left), non-metals are shaded in blue
18Electronic Structure 2.8.1 Electrons are held in shells C2.4 Electron shellsElectronic StructureNo. of electrons in 2nd shell2.8.1No. of electrons in 3rd hellNo. of electrons in 1st shellElectrons are held in shellsThe first shell can hold upto 2 electronsThe second shell can hold upto 8 electronsThe third shell can hold upto 8 electrons