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Atoms, ions & isotopes Click on mouse or press ‘Enter’ to begin. Atoms. An atom is the smallest neutral particle that makes up an element. nucleus. a boron atom. Parts of an atom. Atoms are made up of: a nucleus containing protons and neutrons surrounded by a cloud of electrons.
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Atoms, ions & isotopesClick on mouse or press ‘Enter’ to begin.
Atoms An atom is the smallest neutral particle that makes up an element. web site: www.ktaggart.com
nucleus a boron atom Parts of an atom Atoms are made up of: a nucleus containing protons and neutrons surrounded by a cloud of electrons web site: www.ktaggart.com
Protons,neutrons & electrons web site: www.ktaggart.com
Atoms & ions An atom is a neutrally charged particle This means that: - an atom has an equal number of protons and electrons. • An ion is formed when an atom gains or loses electrons. • this process is called ionisation. • an atom that gains electrons becomes a negative ion. • an atom that loses electrons becomes a positive ion. • ionisation can be caused by radioactivity, heating or high voltages. web site: www.ktaggart.com
Atomic number The atomic number of an atom is equal to the number of protons inside its nucleus. The atomic number of the boron atom is: 5 Atomic number is also called the proton number. web site: www.ktaggart.com
Mass number The mass number of an atom is equal to the number of protons plus neutrons inside its nucleus. The mass number of the boron atom is: 10 mass number is also called the nucleon number. web site: www.ktaggart.com
Isotopes Isotopes are atoms that have the same number of protons but different numbers of neutrons. • This means that they: • have the same atomic number • have different mass numbers • are all of the same element • have identical chemical properties web site: www.ktaggart.com
nucleus nucleus a boron atom with 7 neutrons mass number = 12 a boron atom with 5 neutrons mass number = 10 Two different isotopes of boron web site: www.ktaggart.com
mass number nucleus 10 5 B or atomic number a boron atom Atomic notation This boron atom is written as either: boron 10 web site: www.ktaggart.com
nucleus a carbon 12 atom Question 1 Draw a picture of an atom of carbon 12 if it has 6 protons, 6 neutrons and 6 electrons. web site: www.ktaggart.com
nucleus a lithium 7 atom Question 2 Draw a picture of an atom of lithium if it has an atomic number of 3 and a mass number of 7 • atomic number of three means that the atom has 3 protons and 3electrons. • mass number of 7 means that the atom has (7 - 3) = 4 neutrons. web site: www.ktaggart.com
Question 3 For the picture shown opposite: (a) does it represents an atom, a positive or a negative ion? (b) what is its atomic number? (c) what is its mass number? (a) it is a positive ion because there are more protons than electrons (b) atomic number = 7 (7 protons) (c) mass number = 14 (7 p + 7 n) web site: www.ktaggart.com