A&P Chap 2- key elements, chemical bonds and reaction

12 and 99.9%

how many elements compose the human body

Major elements of the human body

• Oxygen

• Hydrogen

• Carbon

• Nitrogen

• Calcium

• Phosphorus

Lesser elements of the Human Body

• Sulfer

• Potassium

• Sodium

• Chlorine

• Magnesium

• Iron

Matter

anything that occupies space

Atom

smallest unit of an element

chemical symbol

atomic number

number of protons

atomic mass

the sum of protons and neutrons

subatomic particles

• Protons

• Neutrons

• Electrons

Electrons

Number of Protons is equal to the number of

Isotope

-Atoms of the same element with the same number of protons but different number of Neutrons

Molecule

• Substance formed by 2 or more atoms

• bonded by covalent bonds ONLY

• ex.) O₂ , H₂0

Compound

• Substance formed by 2 or more elements

• bonded by ionic or covalent bonds

• ex.) NaCI, H₂0

Chemical bond

A force of attraction between 2 atoms

• Atom combines with another to fill its valence shell

Ionic bonds

• transfers one or more valence electrons to another

• between oppositely charged ions

Ionic Bond Process

Non Polar covalent bond

• two atoms share a pair of electrons equally

• atoms with identical or very similar electro negativities

• EX.) hydrogen (H₂) Oxygen (O₂)

• hydrophobic

Covalent Bonds

• atoms that form molecules by sharing electrons

Polar Covalent Bond

• electrons are shared unequally between two atoms

• different electro negativities

• Hydrophilic

• ex.) water, hydrogen chloride

Hydrogen bonds

• weak intermolecular attraction between a hydrogen atom

• slightly positive and slightly negative