Atoms and the Periodic Table

Atoms are the basic building blocks of all matter. Atoms are the basic building blocks of all matter. Atoms are made up of: Atoms are made up of: 1. Protons—Positively charged particles; found in the nucleus 2. Neutrons—Particles that have no charge; found in the nucleus 3. Electrons—Negatively charged particles; found outside the nucleus

Nucleus containing two protons and two neutrons 1 st energy level containing two electrons

The number of protons and electrons will be the same in a neutral atom. The number of protons and electrons will be the same in a neutral atom.

Elements are made up of atoms. Elements are made up of atoms. Elements: substances that cannot be broken down into simpler chemical substances Elements: substances that cannot be broken down into simpler chemical substances examples: Gold, Iron, and Silver examples: Gold, Iron, and Silver Pure Gold 18-Karat Gold 14-Karat Gold ELEMENT Atoms of:

The Periodic Table is a table with all of the elements found on earth. The Periodic Table is a table with all of the elements found on earth.

How to Read the Periodic Table Chemical Symbol: the letters Chemical Symbol: the letters Atomic Number: found above the chemical symbol Atomic Number: found above the chemical symbol Atomic Mass: found below the chemical symbol Atomic Mass: found below the chemical symbol

Atomic Number = # of protons (= # of electrons) Atomic Number = # of protons (= # of electrons) # of neutrons = atomic mass – atomic # # of neutrons = atomic mass – atomic # Isotope: Atoms of the same element that have different numbers of neutrons Isotope: Atoms of the same element that have different numbers of neutrons two isotopes of Sodium

Ions: atoms that gain or lose electrons; have a positive charge (more protons- called a cation) or a negative charge (more electrons-called a anion) Ions: atoms that gain or lose electrons; have a positive charge (more protons- called a cation) or a negative charge (more electrons-called a anion) Valence Electron Rule (Outermost) Valence Electron Rule (Outermost) 1-3 electrons- lose- positive -cation 1-3 electrons- lose- positive -cation 4- covalent bond (covalent bond-share a pair) 4- covalent bond (covalent bond-share a pair) 5-7 electrons – gain- negative - anion 5-7 electrons – gain- negative - anion 8 –Inert because the atom is full ( Noble gases 8 –Inert because the atom is full ( Noble gases

Electron Shell Diagram and Electron Dot Formula 1 st electron shell can hold 2 electrons 1 st electron shell can hold 2 electrons 2 nd electron shell can hold 8 electrons 2 nd electron shell can hold 8 electrons 3 rd electron shell can hold 8 electrons 3 rd electron shell can hold 8 electrons Nucleus 1st 2nd 3rd

Electron shell diagram: shows the arrangement of all the electrons surrounding the nucleus of an atom Electron shell diagram: shows the arrangement of all the electrons surrounding the nucleus of an atom 6 P 6 N If we have 6 protons in the nucleus, we need to have 6 electrons in the energy levels around the nucleus. The first 2 electrons go in the 1 st energy level. The other 4 electrons go in the 2 nd energy level.

Electron dot formula: shows the number of electrons in the outermost electron shell Electron dot formula: shows the number of electrons in the outermost electron shell C First, you write the symbol for the element. Next, you draw a dot for each electron in the outermost energy level. You can put dots on four sides of the symbol— top, bottom, left, and right. Put the dots in pairs.