Chapter 2: The Chemical Context Of Life Flashcards
Define matter.
Anything that takes up space and has mass
Define an element.
A substance that cannot be broken down to other substances by chemical reactions.
How many known elements have chemists discovered in nature?
92 elements
What is a compound?
A substance consisting of two or more different elements combined in a fixed ratio
What is NaCl made up?
Hint: gas, solid, liquid, ie
Sodium is a metal and chlorine is a poisonous gas
What is an essential element?
An organism needs these to live a healthy life and reproduce
How many essential elements do humans need and how many do plants need?
Humans need 25 and plants need 17
What 4 elements make up 96% of living matter?
Oxygen, carbon, hydrogen, and nitrogen
Define an atom.
Smallest unit of matter that still retains all the properties of the element
What are atoms composed of and what at their charges?
Subatomic particles including protons (positive), neutrons (neutral), and electrons (negative)
Where are protons and neutrons found at in the atom?
The atomic nucleus
How are atoms measured?
With Daltons or atomic mass units
How much does one proton/neutron weigh?
1 AMU
Define the atomic number.
Number of protons found in the atom that makes it into a specific element.
What is the mass number?
Sum of the protons plus neutrons in the nucleus of an atom
What is the name for an atom having more or less neutrons?
An isotope
Define energy
Capacity to cause change
Where are electrons found at?
Electron shells in the cloud
True or false?
Electrons have more energy closer to the nucleus.
False
What happens when an electron absorbs energy?
It moves to a shell farther away from the nucleus
What happens when an electron loses energy?
It falls back to a shell closer to the nucleus and energy is general lost as heat
How many electrons can the second electron shell hold?
8
What is the outer shell and outer electrons known as?
Valence shell and valence electrons
What does inert mean?
Chemically unreactive especially when the valence shell is full
What is the three dimensional space where an electron is found 90% of the time?
An orbital
Define chemical bonds.
When atoms either share or transfer electrons resulting in the atoms staying close together due to their attraction
What is a covalent bond?
Sharing of a pair of valence electrons by two atoms
What represents a single bond?
- a single dash
What represents a double bond?
= an equal sign
What is the atom’s valence?
The number of unpaired valence electrons in an atom
What is the attraction of a particular atom for the electrons of a covalent bond?
Electronegativity
Differentiate between non polar covalent bond and polar covalent bond.
Non polar covalent bond is when the electrons are shared equally because the two atoms have the same electro negativity. A polar covalent bond is where the electrons are not shared equally due to different electro negativities
Define a covalent bond.
Electrons are shared
What is the strongest electronegative element?
Oxygen
What is an ionic bond?
Two atoms are so unequal in electro negativity that the stronger atom takes the electron from the other atom and causes them to attract to each other due to the different charges
What is a positive ion and a negative ion?
Cation is positive and anion is negative
What are ionic compounds also known as?
Salts
True or false?
Not all salts have equal numbers of cations and anions.
True
Define a hydrogen bond.
The partial positive charge of a hydrogen atom and an electronegative atom by a noncovalently
True or false?
Not all chemical reactions are reversible.
False
What is the vanilla plant used in?
Used in lotions, cosmetics, food products, chocolate, ice cream flavor
What is the plant called that we eat the vanilla beans from?
Vanilla planifolia
What plant is in the Orchidaeae family and is a vine type orchid and we eat the beans?
Vanilla planifolia
How many subatomic particles have been identified?
Over 100
How many valence electrons does Na have and how many does Cl have?
Na has 1 and Cl has7
What happens in a chemical reaction when bonds are broken?
Basically matter is being reformed into different makeups and no matter is lost and since matter is not lost, we say matter is conserved
When bonds are broken, we say that energy is _______.
Consumed
Energy is released when bonds are _______.
Formed
