Li Ne K O 3 8 19 10 1. Atomic structure 7 20 39 16 Mass number Atomic number This is a lithium atom. It has an atomic number of 3, this means it has three protons. The periodic table gives you its atomic number and mass number. The atomic number is the number of protons it has. Task 8: How many protons do these elements have? 20 39 16 K Potassium Ne Neon O Oxygen 8 19 10

Li Ne K O 3 8 19 10 2. Atomic structure 7 20 39 16 Mass number Atomic number This is a lithium atom. It has 3 protons and 4 neutrons. It has a mass number of 7 The mass number is the combined number of protons and neutrons. Task 9: How many neutrons do these elements have? 20 39 16 K Potassium Ne Neon O Oxygen 8 19 10

Li Ne K O 3 8 19 10 3. Atomic structure 7 20 39 16 Mass number Atomic number This is a lithium atom. It has 3 protons and 3 electrons. In a neutral atom, the number of electrons is equal to the number of protons. Task 10: How many electrons do these elements have? 20 39 16 K Potassium Ne Neon O Oxygen 8 19 10

4. Electronic structure 2nd shell 3rd shell Electrons orbit the nucleus in shells. Each shell can only hold a set number of electrons. The higher the shell, the more energy the electrons in it have. 1st shell (The one closest the nucleus) 2nd shell 3rd shell Task 11: This is an Argon atom, each of the first three shells is full. What is the number of electrons each shell can hold? 1st Shell = 2nd Shell = 3rd Shell =

5. Electronic structure 1 2 X X X X X The Atomic number tells you the number of protons an atoms has. In a neutral atom then it’s also the number of electrons. X X X Mass number Atomic number X X Helium (He) has an atomic number of 2. This means it has 2 electrons. They fill up the 1st shell. Lithium (Li) has an atomic number of 3. This means it has 3 electrons. 2 fill up the 1st shell and there is 1 in the 2nd shell. Task 12: Complete the 6 electron diagrams and use the periodic table to find the element’s name. 1 2

6. Electronic structure 3 4 5 6

7. Electronic structure Task 13: Use the periodic table to identify these three atoms. 1 3 2

8. Groups 1 Lithium, Sodium and Potassium are all in Group 1 of the periodic table. Task 14: Draw the electron structure for sodium and potassium. What do the three atoms have in common? Lithium Sodium Potassium

9. Groups 2 Fluorine and Chlorine are in Group 7 of the periodic table. Task 15: Draw the electron structure for fluorine and chlorine. What do the two atoms have in common? Task 16: Carbon is in Group 4 of the periodic table. How many electrons will it have in its outer shell? Fluorine Chlorine

Task: Complete the paragraph in your books using the words below. electrons, energy, group, nucleus, shells The electrons in an atom are arranged around the ________ in _______(energy levels). The electrons further away from the nucleus have more ________than those close to the nucleus. All elements in the same _______ of the periodic table have the same number of _________in their outermost shell.