Tuesday, March 31, 2020

The First Thanksgiving Essays - Plymouth, Massachusetts,

The First Thanksgiving THE FIRST THANKSGIVING On September 6, 1620, 102 men, women and children from England boarded a small cargo boat called the Mayflower and set sail for the New World. The passengers left their homes in England in search of religious freedom from the King of England. Today they are known as pilgrims. After braving two months at sea, crossing the stormy Atlantic Ocean, the Pilgrims finally landed off the coast of the New World. In the freezing December waters, they anchored the Mayflower and sent a landing party to what is now Plymouth Harbor beach. To secure the small landing boat against the rain and winds, they tied it to a large rock - Plymouth Rock - and so begins the legend of the original Thanksgiving tale. The Pilgrims found themselves in a harsh new environment. In the middle of winter, they slowly built a settlement at the site of an abandoned Pawtuxet Indian village. Not used to hunting or fishing, they struggled to find food. Many were starving. The future looked bleak. Many of the pilgrims did not survive the first winter. By the time spring arrived, they still had not met the Indians. Instead, they lived in fear of their unseen neighbors based on savage tales they heard from scouts. When April arrived, the crew of the Mayflower raised its sails and set off for England, offering to take any Pilgrim who wished to return to England. Faced with the choice of the harsh New World, or the religious intolerance of the King, they all stayed. One day, a lone Indian man walked into the settlement. He raised his hand in friendship to the settlers. The Pilgrims welcomed this stranger named Samoset. Samoset introduced the Pilgrims to his chief, Massasoit, and his interpreter, Squanto. Squanto spoke English because he had been captured as a boy by traders who had come to the New World in search of slaves. Squanto was taken to England and lived there many years before returning to the New World. He alone understood that the Pilgrims did not know how to hunt or fish - that they would die without help in the New World. Squanto and Chief Massasoit extended their friendship to the Pilgrims. They showed them how to catch fish with nets and how to grow corn, pumpkins, potatoes and squash - foods from the New World. The Indians showed the Pilgrims where to hunt turkey and deer, and where to gather nuts and berries. They explained to the Pilgrims that the land was master of those who walked and lived there. The harvest of 1621 saw the fulfillment of their labors. The Pilgrims had grown barley, corn, pumpkins, and beans. The settlers labored to gather their bounty; and in thanks for their fortune, decided to honor the land with a special day of thanks and celebration. In friendship and gratitude to Squanto, Chief Massasoit and the Indian people, they invited their new friends to join in the feast. The Pilgrims spent days preparing for the feast. The men hunted ducks and turkeys, while the women baked food and decorated the table. When the day finally arrived, the Pilgrims were surprised to see not 10, not 20, but 90 Indians approaching the village! They brought with them a bounty all their own. For three days, the Indians and Pilgrims feasted and gave thanks to the land for the harvest. It was a celebration of friendship and thanks; but most of all, it was a celebration of freedom. Neither the Indians nor the Pilgrims knew what they had begun, but from this celebration emerged Thanksgiving as we know it today. We have been celebrating it as a uniquely American holiday ever since. In 1863, President Lincoln officially declared the last Thursday in November a holiday of thanksgiving and praise, and so it remains today. Happy Thanksgiving! History Essays

Saturday, March 7, 2020

Hydrogen Bond Definition and Examples

Hydrogen Bond Definition and Examples Most people are comfortable with the idea of ionic and covalent bonds, yet unsure about what hydrogen bonds are, how they form, and why they are important. Key Takeaways: Hydrogen Bonds A hydrogen bond is an attraction between two atoms that already participate in other chemical bonds. One of the atoms is hydrogen, while the other may be any electronegative atom, such as oxygen, chlorine, or fluorine.Hydrogen bonds may form between atoms within a molecule or between two separate molecules.A hydrogen bond is weaker than an ionic bond or a covalent bond, but stronger than van der Waals forces.Hydrogen bonds play an important role in biochemistry and produce many of the unique properties of water. Hydrogen Bond  Definition A hydrogen bond is a type of attractive (dipole-dipole) interaction between an electronegative atom and a hydrogen atom bonded to another electronegative atom. This bond always involves a hydrogen atom. Hydrogen bonds can occur between molecules or within parts of a single molecule. A hydrogen bond tends to be stronger than van der Waals forces, but weaker than covalent bonds or ionic bonds. It is about 1/20th (5%) the strength of the covalent bond formed between O-H. However, even this weak bond is strong enough to withstand slight temperature fluctuation. But the Atoms Are Already Bonded How can hydrogen be attracted to another atom when it is already bonded? In a polar bond, one side of the bond still exerts a slight positive charge, while the other side has a slight negative electrical charge. Forming a bond doesnt neutralize the electrical nature of the participant atoms. Examples of Hydrogen Bonds Hydrogen bonds are found in nucleic acids between base pairs and between water molecules. This type of bond also forms between hydrogen and carbon atoms of different chloroform molecules, between hydrogen and nitrogen atoms of neighboring ammonia molecules, between repeating subunits in the polymer nylon, and between hydrogen and oxygen in acetylacetone. Many organic molecules are subject to hydrogen bonds. Hydrogen bond: Help bind transcription factors to DNAAid antigen-antibody bindingOrganize polypeptides into secondary structures, such as alpha helix and beta sheetHold together the two strands of DNABind transcription factors to each other Hydrogen Bonding in Water Although hydrogen bonds form between hydrogen and any other electronegative atom, the bonds within water are the most ubiquitous (and some would argue, the most important). Hydrogen bonds form between neighboring water molecules when the hydrogen of one atom comes between the oxygen atoms of its own molecule and that of its neighbor. This happens because the hydrogen atom is attracted to both its own oxygen and other oxygen atoms that come close enough. The oxygen nucleus has 8 plus charges, so it attracts electrons better than the hydrogen nucleus, with its single positive charge. So, neighbor oxygen molecules are capable of attracting hydrogen atoms from other molecules, forming the basis of hydrogen bond formation. The total number of hydrogen bonds formed between water molecules is 4. Each water molecule can form 2 hydrogen bonds between oxygen and the two hydrogen atoms in the molecule. An additional two bonds can be formed between each hydrogen atom and nearby oxygen atoms. A consequence of hydrogen bonding is that hydrogen bonds tend to arrange in a tetrahedron around each water molecule, leading to the well-known crystal structure of snowflakes. In liquid water, the distance between adjacent molecules is larger and the energy of the molecules is high enough that hydrogen bonds are often stretched and broken. However, even liquid water molecules average out to a tetrahedral arrangement. Because of hydrogen bonding, the structure of liquid water becomes ordered at lower temperature, far beyond that of other liquids. Hydrogen bonding holds water molecules about 15% closer than if the bonds werent present.  The bonds are the primary reason water displays interesting and unusual chemical properties. Hydrogen bonding reduces extreme temperature shifts near large bodies of water.Hydrogen bonding allows animals to cool themselves using perspiration because such a large amount of heat is needed to break hydrogen bonds between water molecules.Hydrogen bonding keeps water in its liquid state over a wider temperature range than for any other comparable-sized molecule.The bonding gives water an exceptionally high heat of vaporization, which means considerable thermal energy is needed to change liquid water into water vapor. Hydrogen bonds within heavy water are even stronger than those within ordinary water made using normal hydrogen (protium). Hydrogen bonding in tritiated water is stronger still.