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Flashcards in Bio Test #3 Deck (31):

How are compounds formed?

Atoms interact with each other forming compounds



Made of 2 or more elements in specific proportions
Ex: H2O & H2CO3


What are compounds held together by?

When atoms form compounds they are held together by atomic bonds


What are 2 types of bonds?

Covalent & ionic



Electrons are shared



Transfer electrons (from one atom to another)


Why do atoms form bonds?

Atoms form bonds according to how electrons are arranged in their orbitals


Noble gases

Atoms are chemically stable when orbitals of its highest level are filled with maximum number of electrons



The simplest part of a substance that retains all the properties of that substance


In an ionic bond, what is done when both elements have unfilled outer orbitals?

They transfer electrons making them both more stable and both gain a charge that keeps them together


Hydrogen Bond

Force of attraction between partially positive charge of one molecule and the partially (or full) negative charge of another molecule


What does partially positive or negative mean?

Electrons turn so they are not always positive or negative


Polar Molecules

Molecules with uneven distribution of charges


How are hydrogen bonds compared to covalent & ionic?

Hydrogen bonds are not as strong as ionic or covalent bonds, they break more easily


How many hydrogen bonds can form from each H2O molecule?



How does a water molecule behave like an electromagnet?

Having the positive end attract a negative ion or negative end of another polar molecule and vice versa


Why does a water molecule behave like an electromagnet?

Because of its polarity


What are properties water exhibit because if its electromagnetism?

Transparency, adhesion, cohesion, solvent, thermal, transport medium, & medium for metabolic reaction



Light can pass through ware



Because of water polarity, water molecules can interact with molecules of other substances. This attraction makes capillary action possible


Capillary Action

Property of water to pull itself up through a small opening against the force of gravity. Important in plants to get water from the soil to the leaves



Because of hydrogen bonds water molecules interact with other water molecules- creating surface tension which allows some animals to use it as a habitat (example: mosquito larvae, spiders can walk on it, "Jesus Lizard"


Solvent Properties

Because of water polarity, water can break bonds between other substances (dissolve substance)


Is water a universal solvent?

Water is a very strong solvent, but it is not a universal solven because if it were, we could not drink it, swim it, hold it in ourselves, store it in a bottle, etc. however water can break bonds between many substances such as: salt & glucose


Thermal properties

Heat capacity, boiling & freezing point, cooling effect of evaporation


Heat capacity

Water has a large amount of energy & is needed to raise water temperature of 1 degree Celsius. This is due to water polarity because a lot of energy is needed to break hydrogen bonds between water molecules. As hydrogen bonds break molecules move faster & this generates heat. Allowing water to be stable & use blood to move heat around the body


Boiling & freezing point

Water having a high boiling point allows for water to change from liquid to gas by breaking all hydrogen bonds. When water freezes it becomes less dense because as molecules slow down, they form hydrogen bonds & spread apart. However the ice that forms at the surface of a lake/ river, creates an insulation layer that allows the water underneath not to freeze


Cooling effect of evaporation

Water can evaporate at temperatures lower than boiling temp. In order for some water molecules to evaporate from the surface, hydrogen bonds need to be broken. The energy used to break the bond is taken from the water itself. Evaporation allows water to cool because When water loses energy it's temp goes down


Why is water a good transport medium?

Because of water solvent properties and how dense water is


Transport medium

Because of its density water can support mass of large & small organisms which live and move in it. Also currents in water help carry nutrients, spores, & organisms from one place to the next. Water is also used in cells & organisms to transport all kinds of nutrients & molecules from one place to the next (ex: water is an important part of digestion, blood, & both vascular tissues


Medium for metabolic reactions

Water is the medium in which most reactions take place & is capable of breaking bonds between compounds & once those compounds are free, they can react with other compounds. Water is not the only medium for reactions, but in most living organisms it is where most metabolic reactions occur