Inside an Atom

The Atom As A Model

Structure of an Atom Atoms consist of protons, electron, and neutrons Atoms consist of protons, electron, and neutrons Protons and neutrons make up the nucleus Protons and neutrons make up the nucleus Protons: + charge Protons: + charge Neutrons: neutral Neutrons: neutral Electrons move around the nucleus Electrons move around the nucleus Electrons: (-) charge Electrons: (-) charge They orbit the nucleus in energy levels They orbit the nucleus in energy levels # of protons and electrons are equal # of protons and electrons are equal

Structure of an Atom Atomic number Atomic number Number of protons in an element Number of protons in an element Hydrogen – Atomic number is 1 Hydrogen – Atomic number is 1 Atomic mass Atomic mass Amu – atomic mass unit Amu – atomic mass unit Total number of protons and neutrons in an element Total number of protons and neutrons in an element Isotopes Isotopes Isotopes have the same number of protons but a different number of neutrons Isotopes have the same number of protons but a different number of neutrons Ex: carbon-12, carbon-13, and carbon-14 Ex: carbon-12, carbon-13, and carbon-14

11 Na Sodium Problem a.What is the atomic number? b.What is the mass number? c.How many electrons? Protons? Neutrons

Modern Periodic Arrangement Horizontal rows are called periods Horizontal rows are called periods Vertical columns are called groups or families. Vertical columns are called groups or families. These elements have similar properties These elements have similar properties periodic table song periodic table song periodic table song periodic table song

Electron Sharing Covalent bond – a bond in which electrons are shared between atoms to form molecules Covalent bond – a bond in which electrons are shared between atoms to form molecules Both atoms will have 8 valence electrons Both atoms will have 8 valence electrons

Ionic Bonds An atom that has gained or lost an electron is called an ion An atom that has gained or lost an electron is called an ion Ions have an electrical charge Ions have an electrical charge

Ionic Bonds

What Happens When Chemicals React? Some cool chemical reactions Reaction of sodium and chlorine

Exothermic vs. Endothermic Exothermic reactions release heat Exothermic reactions release heat Become warmer Become warmer Endothermic reactions absorb heat Endothermic reactions absorb heat Become cooler Become cooler