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Inside an Atom. All matter is made up of one or more elements All matter is made up of one or more elements Element: substance that cannot be broken.

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Presentation on theme: "Inside an Atom. All matter is made up of one or more elements All matter is made up of one or more elements Element: substance that cannot be broken."— Presentation transcript:

1 Inside an Atom

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3 All matter is made up of one or more elements All matter is made up of one or more elements Element: substance that cannot be broken down into smaller substances Element: substance that cannot be broken down into smaller substances Examples: Hydrogen, Carbon, Oxygen Examples: Hydrogen, Carbon, Oxygen Atom: the smallest unit of an element Atom: the smallest unit of an element

4 Parts of an Atom Proton – positive charge (+) Proton – positive charge (+) Neutron – neutral (no charge) Neutron – neutral (no charge) Electron – negative charge (-) Electron – negative charge (-)

5 Protons and neutrons are found in the nucleus in the center of the atom Protons and neutrons are found in the nucleus in the center of the atom Electrons are moving rapidly in a cloud around the nucleus Electrons are moving rapidly in a cloud around the nucleus Different energy levels around the nucleus Different energy levels around the nucleus Electrons may “hang out” in these levels Electrons may “hang out” in these levels Valence electrons – those that are farthest from the nucleus and most loosely held Valence electrons – those that are farthest from the nucleus and most loosely held

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7 Properties of Atoms An atom is neutral when it has an equal number of protons (+) and electrons (-). An atom is neutral when it has an equal number of protons (+) and electrons (-). Sometimes when one atom reacts with another atom, it gains or loses an electron giving it a positive or negative charge Sometimes when one atom reacts with another atom, it gains or loses an electron giving it a positive or negative charge This charged particle is called an ION This charged particle is called an ION

8 If an atom loses an electron (-), it now has a positive charge (cation) If an atom loses an electron (-), it now has a positive charge (cation) If an atom gains an electron (-), it now has a negative charge (anion) If an atom gains an electron (-), it now has a negative charge (anion) Properties continued…

9 More Properties Atomic Number – number of protons Atomic Number – number of protons Identifies and determines the element Identifies and determines the element Carbon: atomic # 6 Carbon: atomic # 6 Sodium: atomic # 11 Sodium: atomic # 11 Gold: atomic # 79 Gold: atomic # 79 Atomic mass – average mass of one atom of an element Atomic mass – average mass of one atom of an element

10 Atomic Mass Unit (amu) SI unit used to measure the mass of particles in atoms SI unit used to measure the mass of particles in atoms Protons and Neutrons = 1 amu Protons and Neutrons = 1 amu Approximately 2000 Electrons = 1 amu Approximately 2000 Electrons = 1 amu Almost all of an atom’s mass is in the nucleus Almost all of an atom’s mass is in the nucleus

11 Isotopes The number of protons for a certain atom never changes, but sometimes an atom may have different numbers of neutrons The number of protons for a certain atom never changes, but sometimes an atom may have different numbers of neutrons Mass Number – sum of protons and neutrons Mass Number – sum of protons and neutrons

12 Hydrogen Isotopes


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