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Basic Chemistry Define: Chemistry & Biochemistry

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1 Basic Chemistry Define: Chemistry & Biochemistry

2 All matter is composed of atoms
Basic Chemistry Chemistry is the study of matter Anything that has volume and takes up space Solid, liquid, and gas Exists as elements in pure form and in chemical combinations called compounds Organism All matter is composed of atoms

3 Each element has its own unique symbol
Basic Chemistry Atoms The smallest unit of an element that still retains the properties of an element Elements A substance made of only one kind of atom Cant be broken down into simpler substances by a chemical reaction Ex: Iron is an element – it consists of only iron atoms Hydrogen and helium are by far the most abundant elements in the universe. However, iron is the most abundant element (by mass) making up the Earth, and oxygen is the most common element in the Earth's crust.[ Each element has its own unique symbol

4 arranged according to similar properties and atomic number
FACTS: 118 known elements 92 occur in nature arranged according to similar properties and atomic number 92 occur naturally Over 92 were made in a lab Vertical columns contain elements with similar properties 6 elements found in living things: carbon, hydrogen, oxygen, nitrogen, silicon, phosphorus – make up 98% of living things

5 Elements of Life 96% of living organisms is made of: carbon (C)
hydrogen (H) oxygen (O) nitrogen (N)

6 Other Elements A few other elements make up the remaining 4% of living matter Table 2.1

7 (a) Nitrogen deficiency (b) Iodine deficiency (Goiter)
Deficiencies If there is a deficiency of an essential element, disease results (a) Nitrogen deficiency (b) Iodine deficiency (Goiter) Figure 2.3

8 Trace Elements Trace elements Are required by an organism in only minute quantities Minerals such as Fe and Zn are trace elements

9 Explain the relationship between an atom and an element.
What are the four major elements that make up living organisms?

10 Compounds Are substances consisting of two or more elements combined in a fixed ratio Have characteristics different from those of their elements Sodium Chloride Sodium Chloride + Figure 2.2

11 Molecule of Glucose

12 Atomic Structure Atoms of each element are composed of subatomic particles Nucleus Protons (p+) Neutrons (n0) Outside of nucleus Electrons (e-) in a cloud, electron shells

13 Carbon has ___ p+ and ___ e-
Identifying Elements Atoms of various elements differ in their number of subatomic particles C 12.011 6 Atomic Number = # of p+ and # of e- 6 Carbon has ___ p+ and ___ e- 6 protons (+) = electrons (-) Atoms are electrically NEUTRAL Atomic Mass = # protons + # neutrons 6 Carbon has ___ n0

14 C Atomic number – the number of protons – unique to each element
Electron configuration – placement of electrons in energy levels 2 4 6 Atomic symbol – used to represent both the element and one atom of that element C Carbon Mass number – number of protons plus the number of neutrons 12.011 12 Atomic mass – the total mass of the atom – sum of the mass of the protons and neutrons – average mass of all isotopes

15 Identifying Elements Practice
Atomic number Mass number

16 Identifying Elements Practice

17 Identifying Elements Practice

18 Identifying Elements Isotopes – varieties of an element that have different number of neutrons Same number of protons, different neutrons Same ____________, different ____________

19 Other uses Can be used in medicine to treat tumors
Cancerous throat tissue Figure 2.6

20 Energy Energy Potential energy
Is defined as the capacity to cause change Potential energy - Is the energy that matter possesses because of its location or structure Kinetic Energy - Is the energy of motion

21 Electrons and Energy The electrons of an atom
Differ in the amounts of potential energy they possess A ball bouncing down a flight of stairs provides an analogy for energy levels of electrons, because the ball can only rest on each step, not between steps. (a) Figure 2.7A

22 Energy Levels of Electrons
An atom’s electrons vary in the amount of energy they possess Electrons further from the nucleus have more energy Electron’s can absorb energy and become “excited” Excited electrons gain energy and move to higher energy levels or lose energy and move to lower levels

23 Energy Levels Are represented by electron shells
Third energy level (shell) Second energy level (shell) First energy level (shell) Energy absorbed lost An electron can move from one level to another only if the energy it gains or loses is exactly equal to the difference in energy between the two levels. Arrows indicate some of the step-wise changes in potential energy that are possible. (b) Atomic nucleus Figure 2.7B

24 Why do elements react? The number of valance electrons determine the chemical behavior of an element Atoms seek to have “full” outer most electron shells

25 Covalent Bonds The sharing of a pair of electrons
Results in a molecule Two or more atoms combine and act as a single particle Example: H2O (water) Hydrogen Atom Oxygen Atom = WATER MOLECULE 1+ 8+ wants to fill this

26 Multiple Covalent Bonds
Name (molecular formula) Electron- shell diagram Structural formula Space- filling model Hydrogen (H2). Two hydrogen atoms can form a single bond. Oxygen (O2). Two oxygen atoms share two pairs of electrons to form a double bond. H O Figure 2.11 A, B (a) (b)

27 Compounds & Covalent Bonds
Name (molecular formula) Electron- shell diagram Structural formula Space- filling model (c) Methane (CH4). Four hydrogen atoms can satisfy the valence of one carbon atom, forming methane. Water (H2O). Two hydrogen atoms and one oxygen atom are joined by covalent bonds to produce a molecule of water. (d) H O C Figure 2.11 C, D

28 Covalent Bonding Electronegativity The more electronegative an atom
Is the attraction of a particular kind of atom for the electrons in a covalent bond The more electronegative an atom The more strongly it pulls shared electrons toward itself

29 Covalent Bonding In a nonpolar covalent bond
The atoms have similar electronegativities Share the electron equally

30 Covalent Bonding In a polar covalent bond
The atoms have differing electronegativities Share the electrons unequally This results in a partial negative charge on the oxygen and a partial positive charge on the hydrogens. H2O d– O H d+ Because oxygen (O) is more electronegative than hydrogen (H), shared electrons are pulled more toward oxygen. Figure 2.12

31 Ionic Bonds Formed by the transfer of electrons between atoms
Results in ions an atom that has lost or gained electrons = electric charge Example: NaCl (table salt) Chlorine Ion -1 (Anion) Chlorine Atom Sodium Atom Sodium Ion +1 (Cation) 11+ 17+

32 Ionic Substances Ionic compounds
Are often called salts, which may form crystals Figure 2.14 Na+ Cl–

33 Weak Chemical Bonds Several types of weak chemical bonds are important in living systems This includes: hydrogen bonds Van der Waals interactions Weak chemical bonds are important because Reinforce the shapes of large molecules Help molecules adhere to each other

34 Van der Waals Interactions
Even non-polar molecules can have some positively and negatively charged region briefly and can very weakly bind to another. Plasma membrane are stabilized by the additive affect of Van der Waals interactions between non-polar fatty acid tails of phospholipids.

35 Hydrogen Bonds H bonds The two strands of a DNA molecule are held together tightly by the additive affect of many, many weak Hydrogen Bonds Forms when a hydrogen atom that is covalently bonded to on electronegative atom is attracted to another electronegative atom Formed between two partially charged atoms Weaker than ionic bonds

36 Molecules of Life Put C, H, O, N together in different ways to build living organisms What are bodies made of? carbohydrates sugars & starches proteins fats (lipids) nucleic acids DNA, RNA

37 Molecular Shape Determines Function
Determines how biological molecules recognize and respond to one another with specificity Morphine Carbon Hydrogen Nitrogen Sulfur Oxygen Natural endorphin (a) Structures of endorphin and morphine. The boxed portion of the endorphin molecule (left) binds to receptor molecules on target cells in the brain. The boxed portion of the morphine molecule is a close match. (b) Binding to endorphin receptors. Endorphin receptors on the surface of a brain cell recognize and can bind to both endorphin and morphine. Endorphin receptors Brain cell

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