ATOMIC STRUCTURE 8A1 ALYSSA

ATOM What Is an Atom? An atom is the basic unit of an element. An atom is a form of matter which may not be further broken down using any chemical means. A typical atom consists of protons, neutrons and electrons.

What is helium ? HELIUM ATOM Helium is the name for the element with atomic number 2 and is represented by the symbol He. It is a member of the noble gases group. What is helium ? Shell N - + proton N + - neutron electron This is helium atom

number of electrons = number of protons HELIUM ATOM He 2 Atomic number The number of protons in an element. Examples: The atomic number of hydrogen is 1; the atomic number of carbon is 6. Also Known As: The atomic number is also known as the proton number. It may be represented by the capital letter Z. 4 Atomic mass the number of protons and neutrons in an atom number of electrons = number of protons

ATOMIC STRUCTURE Electrons are arranged in Energy Levels or Shells around the nucleus of an atom. first shell: a maximum of 2 electrons second shell: a maximum of 8 electrons third shell: a maximum of 8 electrons

1.Electronic Configuration ATOMIC STRUCTURE There are two ways to represent the atomic structure of an element or compound: 1.Electronic Configuration 2.Dot & Cross Diagrams

ELECTRONIC CONFIGURATION With electronic configuration elements are represented numerically by the number of electrons in their shells and number of shells. For example: Helium configuration = 2 2 2 in 1st shell He 4

He DOT & CROSS DIAGRAMS Helium With Dot & Cross diagrams elements and compounds are represented by Dots or Crosses to show electrons, and circles to show the shells. For example: Helium He 2 X He X 4

SUMMARY The Atomic Number of an atom = number of protons in the nucleus. The Atomic Mass of an atom = number of Protons + Neutrons in the nucleus. The number of Electrons = Number of Protons. . 4. Each shell can only carry a set number of electrons.

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