1.1 Structure Of Water And Hydrogen Bonding Flashcards
What is matter?
- anything that takes up space and has mass
Ex. Rocks, metals, oils, gases, organisms, etc.
What is an element? How many occur in nature? (2)
- A substance that cannot be broken down into another substance by chemical reactions
- 92 elements occur in nature
(Periodic table)
What is a compound?
- A substance consisting of two or more different elements combined in a fixed ratio
Ex. H20, NaCl
What percentage of the 92 Naturally occurring elements are essential?
20-25% are essential to survive and reproduce
What essential elements make up a large amount of living matter, and what percent do they make up? (3)
- CHNOPS
- 96% living matter
- Sulfur is in protein R groups
What are trace elements?
- Of the 92 naturally occurring elements, these are required by an organism in very small quantities
Ex. Fe, Mg, Ca, etc.
Why are essential elements essential? In other ways, what roles do they play in the human body?
CHNOP(S) please a vital role in the formation of cells and cellular components
Ex. Proteins, nucleic acids, etc.
What are a few examples of trace elements in their purpose in the human body? Use iron, zinc and copper as an example. (3)
Iron- necessary for blood production
Copper - works with iron to produce blood cells
Zinc - helps the body’s immune system
Which way do groups and periods go on the periodic table?
- Groups are vertical
- periods are horizontal
What does the Bohr model show? (3)
- shows electrons orbiting the nucleus of an atom
- electrons are placed on shells around the nucleus
- each shell is a different energy level and can hold up to a certain number of electrons
What is the Lewis dot model? (4)
- simplified Bohr diagrams
- does not show energy levels
- only shows electrons in the valence shell
- Electrons are placed around the element symbol
Why do elements form chemical bonds with other elements?
- They want to be stable
What is the octet rule?
- elements will gain, lose, or share electrons to complete their valence shell and become stable (like noble gases)
What is a chemical bond?
- Attraction between two Atoms, resulting from the sharing or transferring of valence electrons
What is electronegativity?
- The measure of an atoms ability to attract electrons to itself
What is a covalent bond? (3)
- when two or more atoms share electrons
- usually between two nonmetals
- forms molecules and compounds
What are the two types of covalent bonds?
-polar and non polar
What is a non-polar covalent bond?
- Electrons are shared equally between two atoms
Ex. O2, HOFBrINCl
What is a polar covalent bond? (2)
- electrons are not shared equally between two atoms
Ex. H2O - unequal sharing of Electrons results in partial charges on oxygen and hydrogen
What is an ionic bond?
- The attraction between oppositely charged atoms (ions)
- usually between a metal and nonmetal, where metals transfer electrons to nonmetals
What do Ionic bonds form?
- Ionic compounds and salts
Ex. NaCl, LiF
What are cations and anions?
- positively charged ions and cations
- negatively charged ions are anions
How do hydrogen bonds form? (2)
- The partially positive hydrogen atom in one polar covalent molecule will be attracted to one electronegative atom in another polar covalent molecule
- H bonds are known to be weak
- INTERMOLECULAR
What is the difference between inter-and intramolecular bonds?
- Bonds that form between molecules are INTER
- Intra means inside
Why do hydrogen bonds occur?
- when a hydrogen atom is bonded to an electronegative atom (usually O, N, or F) the electrons are not being shared equally between atoms (remember it’s a covalent bond)
- This causes oxygen to have a partial positive charge on the electronegative atom to have a partial negative charge
How do the hydrogen bonds change the structure of water?
- hydrogen bonds between water make it more structured than most liquids
- water molecules move a lot because hydrogen bonds form, break, and reform with great frequency
