Atoms and Chemical Bonds

1
Atoms and Chemical Bonds
2
Atoms Electrons

• Atoms The basic unit of matter. Atoms have a
  neutral charge because they have equal s of
  protons and electrons.
• The subatomic particles that make up atoms are
• Protons Positive Charge
• Electrons Negative Charge
• Neutrons no charge
• Nucleus Created by strong forces that bind
  protons and neutrons together. Found in the
  center of the atom
• Electrons Are negatively charged and are in
  constant motion around the atoms nucleus

3
Elements Isotopes

• Element Pure substance that consists entirely of
  ONE type of atom
• EX C (Carbon), H (Hydrogen), Na (Sodium)
• Isotopes Atoms of the same element with
  different s of neutrons
• Because they have the same of electrons all
  isotopes of an element still have the same
  chemical properties

4
Radioactive Isotopes

• Some isotopes are radioactive- meaning their
  nucleus is unstable and breaks down at a constant
  rate over tiem
• Can be beneficial because
• Can determine age of rocks by analyzing isotopes
  found in them
• Radiation can be used to treat cancers
• Radioactive Isotopes can be used as tracers to
  follow the movements of substances within
  organisms

5
Chemical Compounds

• In nature most elements are found combined with
  other elements to form compounds
• Compound A substance formed by combining two or
  more elements in definite proportions
• EX NaCl table salt 1 atom of Na 1 atom of Cl
• The physical and chemical properties of compounds
  are usually very different from the elements that
  form it
• EX H and O are gasses at room temperature, but
  combine to form liquid water

6
Chemical Bonds

• Atoms in chemical compounds are held together by
  chemical bonds
• Bond formation uses the electrons that surround
  the atoms nucleus
• The Two Main Types of Chemical Bonds Are
• Ionic Bonds
• Covalent Bonds

7
Ionic Bonds

• Ionic Bonds Formed when one or more electrons
  are transferred from one atom to another
• An atom that loses an electron ends up with a
  positive charge
• An atom that gains an electron ends up with a
  negative charge
• Ions Positively or Negatively charged atoms

8
Covalent Bonds

• Covalent Bonds Electrons are shared between
  atoms
• Sharing occurs when electrons move between the
  orbitals of both atoms
• Sharing 2 atoms single covalent bond
• Sharing 4 atoms double covalent bond
• Sharing 6 atoms triple covalent bond

9
Molecules

• Molecules Structure that forms when atoms are
  joined together by covalent bonds
• Smallest unit of most compounds
• EX Water molecule forms from 1 atom of oxygen
  and 2 atoms of hydrogen that are covalently bonded