Chapter 6

The chemistry of life

Section 6.1 pages 141-151

•Why do we study chemistry in biology?

A possible explanation……………

• Life is driven by metabolism, which is a collection of biochemical reactions that are responsible for everything from energy production to protein synthesis. A firm chemistry foundation is needed to understand these fundamental processes. Without chemistry, a biologist can only deal with the macroscopic and the phenotypical.

Another possible explanation…….pg 140 in your text

• “Living organisms are made of simple elements as well as complex carbon compounds. With an understanding of these elements and compounds, you will be able to relate them to how living organisms function.”

Elements•Page 141•Substance that can’t be broken down into a simpler chemical substance

• Elements occur naturally in nature. There are 116

• Only 25 are essential to living organisms

• 4 elements: carbon, hydrogen, oxygen, and nitrogen make up 96% of the mass of the human body

Page 142 table 6.1

• You need to know this table for the chapter 6 test. Know all element names and symbols on this chart. Know the % mass in the human body for oxygen, carbon, hydrogen, nitrogen, calcium, phosphorus and potassium

Trace elements

• Some of the elements in table 6.1 are present in living things in very small amounts. They are known as trace elements.

• They play a vital role in maintaining healthy cells in all organisms

• Trace elements are obtained by plants via the roots and by animals via the food they eat

Atoms• The smallest particle of an element

that still has properties of the element• Atoms are the basic building blocks of

all matter• 100 million (side by side) would equal

about 1cm in length• Made of subatomic particles

The structure of an Atom

• Nucleus- 99% of mass of the atom• In the nucleus: subatomic particles present: protons

(+) and neutrons • Atomic number- the number of protons in an

element- therefore it’s also the number of electrons in an element. Distinguishing characteristic

• Mass number- number of protons and neutrons. “mass of the nucleus” (appropriate since the nucleus is 99% of the mass of the atom)

• Subatomic particles called electrons are located in the energy levels around the nucleus.

• The first energy level can hold a max of 2 electrons

• The second energy level can hold a max of 8 electrons

• The third energy level can hold a max of 18

Atomic Structure

Atomic Structure- you try it!

• Draw an atom of Calcium• Calcium is needed for blood clotting,

formation of bones and teeth, and normal nerve and muscle formation– Atom’s nucleus first…..how many subatomic

particles?– Energy level 1-holds 2 electrons max– The second energy level holds 8 electrons max– The third energy level holds 18 electrons max

Calcium atomic # 20 atomic mass 40

Isotopes•Atoms of the same element always have the same number of protons but contain different numbers of neutrons

Figure 6.4 on page 144

•Radioactive isotopes•NOT on test….just interesting information

What is an atomic or nuclear bomb?

• A general name given to any weapon in which the explosion results from the energy released by a reaction involving atomic nuclei, either by fission—of uranium or plutonium; or, fusion—of a heavier nucleus with two lighter hydrogen ones. Thus, the A-for atomic bomb, and the H, for hydrogen bomb are both nuclear weapons. In the history of the modern world as we know it, the atomic bomb was only used once to kill human beings: it was dropped on the Japanese people in Hiroshima and Nagasaki in 1945.

• http://www.youtube.com/watch?v=0ipE4w0iUPA

• http://www.youtube.com/watch?v=qB3SuNGIyCE

Mushroom clouds of atomic bombs

• A mushroom cloud is a distinctive pyrocumulus mushroom-shaped cloud of condensed water vapor or debris resulting from a very large explosion. They are most commonly associated with nuclear explosions, but any sufficiently large blast will produce the same sort of effect. They can be caused by powerful conventional weapons like the GBU-43/B Massive Ordnance Air Blast bomb. Volcano eruptions and impact events can produce natural mushroom clouds.

• Mushroom clouds form as a result of the sudden formation of a large mass of hot, low-density gases near the ground creating a Rayleigh–Taylor instability. The mass of gas rises rapidly, resulting in turbulent vortices curling downward around its edges, forming a vortex ring and drawing up a column of additional smoke and debris in the center to form its "stem". The mass of gas eventually reaches an altitude where it is no longer of lower density than the surrounding air and disperses, the debris drawn upward from the ground scattering and drifting back down, otherwise known as “fallout”.

• As it rises, air is drawn upwards and into the cloud (similar to the updraft of a chimney), producing strong air currents known as "afterwinds", while inside the head of the cloud, the hot gases rotate in a toroidal shape. When the detonation altitude is low enough, these afterwinds will draw in dirt and debris from the ground below to form the stem of the mushroom cloud.

• After the mass of hot gases reaches the equilibrium level, the ascent stops and the cloud starts forming the characteristic mushroom shape.

After effects of an atomic explosion

• Much of the destruction caused by a nuclear explosion is due to blast effects.

• Nuclear weapons emit large amounts of thermal radiation as visible, infrared, and ultraviolet light. The chief hazards are burns and eye injuries. On clear days, these injuries can occur well beyond blast ranges. The light is so powerful that it can start fires that spread rapidly in the debris left by a blast.

Problem solving lab 6.1 page 145

• Work alone• Answer questions 1-4• Turn in before the bell rings