Matter & the Elements of Life

1. Matter & the Elements of Life (Organic chemistry)

2. Composition of Matter • Matter - Everything in universe is composed of matter • Matter is anything that occupies space or has mass • Mass – quantity of matter an object has • Weight – pull of gravity on an object

3. Definitions Elements are substances that cannot be broken down chemically into simpler substances. Atoms are the smallest units of an element that still have the chemical properties of that element.

4. Definitions Molecules are made of 2 or more atoms that have combined chemically. Compoundsare made of atoms of 2 or more different elements that have combined chemically in a fixed ratio.

5. Molecules may be made from more than one type of atom or from atoms of the same type. Compounds are only made from more than one type of atom. The water molecule is the only compound in the diagram

6. The Structure of Atoms Atoms themselves are built of 3 types of smaller subatomic particles. a proton has a positive electrical charge an electron carries a negative electrical charge a neutron has no charge (it is neutral)

7. Subatomic Particles Particle Symbol Mass Charge Location --------------------------------------------------------------- proton p+ 1 positive nucleus neutron n 1 neutral nucleus electron e- 0* negative cloud *Actually, an electron has a mass, but it’s very small: 1,867 times smaller than the proton or the neutron

8. Elements Are 92 naturally occurring elements, each has a unique symbol

9. Each element unique chemical symbol • consists of 1-2 letters • First letter is always capitalized

10. Atomic Number 6 Atomic Symbol C Atomic Mass 12.00

11. Atomic Number- Number of protons in a atom • Atomic Mass- Number of protons and neutrons

12. In a normal atom, # protons = #neutrons = # electrons

14. Isotopes -Atoms of the same element that have different numbers of neutrons.

15. Ions – Atoms of the same element that have lost or gained an electron Electrons - Negatively charged high energy particles with little or no mass So, lose a – electron and you have a +(positive) ion So, gain a – electron and you have a – (negative) ion

17. BUILD an ATOM

18. Remember that electrons spin outside the nucleus in a cloud – but in the cloud; they spin at distinct orbits – or shells. Each shell will hold a specific # of electrons

19. The chemical behavior of an atom is determined the distribution of electrons in its electron shells. • The first electron shell can hold only 2 electrons. • Atoms with more than two electrons must place the extra electrons in higher shells. • The second shell can hold up to 8 electrons.

20. The chemical behavior of an atom depends mostly on the number of electrons in its outermost shell, the valence shell. • Electrons in the valence shell are known as valence electrons.

21. Chemical Bonds: attraction, sharing, or transfer of valence electrons from one atom to another

22. Attraction between ions: results in Ionic bond

23. Sharing of electron(s): results in covalent bond Video clip

24. Covalent bond strength depends on the number of electron pairs shared by the atoms. single bond double bond triple bond < <

26. An atom will make covalent bonds until its valence shell is full Video clip

27. Sometimes electrons are not shared equally……. So one side of the molecule has the electrons more than the other……. And so one side of the molecule is more negatively charged and the other side is more positively charged This is called a polar covalent bond

29. Elements can combine chemically in many ways to form the millions of compounds that give Earth its variety of materials. But only FOUR elements make up 96% of living matter. Which ones?

31. So in organic chemistry, we focus only on the compounds that contain these four elements CARBON HYDROGEN NITROGEN OXYGEN