College of Computer, Mathematical and Natural SciencesBSCI201Human Anatomy and Physiology IOpoku-EduseiChapter Two Notes1.Composition of Mattera.Matter- anything that occupies space and has massa.i.Composed of elements- each element is composed of identical atoms a.ii.Atoms are therefore known as the building blocks of matter a.iii.There are 112 elements- most of the body’s weight is made up of four major elements- 86% of the weight of the human body is made up of Carbon, Oxygen, Hydrogen and Nitrogen. 2.Structural organization of the human bodya.Lowest level- chemical levelb.Chemical level Biochemical reaction Physiology functions of the parts in the body c.Basis for biochemical reactions 3.The Structure of an Atoma.Each atom is composed of 3 subatomic particles:a.i.Protons- positively chargedsubatomic particles located in the center of the atom known as he atomic nucleus; number of protons in an atom is specifically referred to as the atomic numbera.ii.Neutrons- uncharged subatomic particles located inside the atomic nucleus a.ii.1.Therefore, the overall charge of the atomic nucleus is positive a.iii.Electrons- negatively-charged subatomic particles located in the orbits/shells surrounding the atomic nucleus. a.iv.In atoms, the number of protons = the number of electrons; therefore the overall charge of an atom is zero- an atom is electrically neutralb.Atomic Structure:b.i.Atomic Nucleusb.i.1.Protons- positively chargedb.i.2.Neutrons- no chargeb.ii.Orbitals (Shells)b.ii.1.Electrons are located/arranged in the orbits/shells in a specific manner: b.ii.1.a.First shell (closest to the atomic nucleus)- can accommodate a maximum of 2 electronsb.ii.1.b.Second shell- can accommodate a maximum of 8 electrons
b.ii.1.c.Third shell- can accommodate a maximum of 18 electrons however, the atom is stable with 8 electrons (“The Octotet rule”)b.ii.2.The outermost shell in an atom is called the valence shell and the electrons located in the valence shells are called valence electrons b.ii.3.If the valence shell of an atom does not contain the maximum number of electrons, the atom is unstable, and therefore chemical reactive.b.ii.4.Example: Na atomic number 11b.ii.4.a.Has 11 protonstherefore 11 electronsb.ii.4.b.2 electrons in first shell, 8 in second, 1 in thirdb.ii.4.c.Sodium atom will achieve stability with a complete outermost orbital, hence it loses the one electron in the third shellb.ii.4.d.Now has two complete shells b.ii.4.e.Now Na+ 1.3 Types of Chemical Bonds a.Covalent Bonds- electrons are shared between atoms to attain stability; 2 types of Covalent Bonds: Nonpolar and Polara.i.Nonpolar covalent bond- electrons are shared equally between the atoms involved; ex CO2(Carbon Dioxide)a.ii.Polar covalent bond- unequal sharing of electrons- one atom pulls the shared electrons closer to itself and such an atom is referred to as an electronegative atom. The other atom is referred to as an electropositive atom; ex H20 a.ii.1.Oxygen = electronegative atoma.ii.2.