Each kind of atom or molecule can gain or lose energy only in particular discrete amounts. When an atom gains energy, light at the wavelength associated with that energy is absorbed. When an atom loses energy, light at the wavelength associated with that energy is emitted. These wavelengths can be used to identify elements. Nuclear Reactions In a nuclear reaction, energy can be converted to matter and matter can be converted to energy. In such processes, energy and matter are conserved, according to Einstein’s formula E = mc 2 ,where E is the energy, m is the mass (matter), and c is the speed of light. A nuclear reaction is different from a chemical reaction because in a nuclear reaction, the particles in nuclei (protons and neutrons) interact, whereas in a chemical reaction, electrons are lost or gained by an atom. Two types of nuclear reactions are fusion and fission. Fusion is a nuclear process in which two light nuclei combine to form one heavier nucleus. A fusion reaction releases an amount of energy more than a million times greater than the energy released in a typical chemical reaction. This gain in energy is accompanied by a loss of mass. The sum of the masses of the two light nuclei is lower than the mass of the heavier nucleus produced. Nuclear fusion reactions are responsible for the energy output of the sun. Fission is a nuclear process in which a heavy nucleus splits into two lighter nuclei. Fission reaction was used in the first atomic bomb and is still used in nuclear power plants. Fission, like fusion, liberates a great amount of energy. The price for this energy is a loss in mass. A heavy nucleus that splits is heavier than the sum of the masses of the lighter nuclei that result. Key Concepts This chapter gave you a crash course in the basics of physical science. Here are the most important concepts to remember: ➧ All matter is composed of tiny particles called atoms. ➧ Atoms combine with other atoms to form molecules. ➧ In a chemical reaction, atoms in molecules rearrange to form other molecules. ➧ The three common states of matter are solid, liquid, and gas. ➧ The disorder in the universe is always increasing. ➧ Mass and energy can’t be created or destroyed. ➧ Energy can change form and can be trans- ferred in interactions with matter. – PHYSICAL SCIENCE– 231 [...]... growth Overcrowding occurs when there are too many individuals living in an area—to the point where most of the individuals in the population live in substandard or poor conditions because of lack of work and lack of living space Mexico City, Istanbul, China, and India are some examples of places in the world experiencing overcrowding How Will Overpopulation Affect Us? Overpopulation can cause serious... and poor hygiene are factors that can affect health and the body’s ability to function properly An unhealthy body is prone to diseases and other hazards found in the environment There are two kinds of diseases: infectious and noninfectious 249 – PERSONAL AND SOCIAL PERSPECTIVES IN SCIENCE – Infectious Disease Staying healthy by caring for the body is important in fighting and preventing disease Poor hygiene... HISTORY AND NATURE OF SCIENCE – shake the foundations of understanding and lead to new modes of thinking Thomas Kuhn, philosopher of science, called such discoveries paradigm shifts Here are some major advances in science ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 260 420 B.C.: Hippocrates begins the scientific study of medicine by maintaining that diseases have common causes 260 B.C.: Archimedes discovers the principle of. .. people, can t help having once in a while “Man can t help hoping even if he’s a scientist He can only hope more accurately.” —Karl Menninger, psychiatrist Controversies Conflicting data, or facts that seemingly can t be incorporated into the same theory, often cause controversies among scientists The controversies can polarize the scientific community, as well as the general population, especially in matters... contributions of individuals from different disciplines, including engineering The Human Genome Project, designed to map the human genome, involved thousands of researchers worldwide and was the largest, most expensive project in the history of biology New disciplines of science, such as geophysics and biochemistry, often emerge at the interface of two older disciplines Technological knowledge is often not... to bring out certain qualities or to embed qualities that the product would not normally have For example, Florida oranges grow best in Florida because oranges prefer lots of sun and warm temperatures Genetic engineering can modify the trees so that the oranges can grow in colder climates, like further north Environmental Quality Many factors contribute to environmental quality Pollution, the introduction... most other living beings have a natural built -in disease-fighting mechanism known as the immune system The immune system is composed of cells, molecules, and organs that defend the body against pathogens The immune system is responsible for finding the pathogen in the body and killing it, rendering it harmless, or expelling it from the body 250 – PERSONAL AND SOCIAL PERSPECTIVES IN SCIENCE – The development... can cause chemical and physical changes in igneous and sedimentary rocks to form metamorphic rocks When exposed to higher temperatures, metamorphic rocks may be partially melted, resulting in the creation once again of igneous rocks, starting the cycle all over again Molten material from inside the earth often breaks through the floor of the ocean and flows from fissures Origin of the Earth and the Solar... responsible for delivering the electricity we use every day, for the refrigerator that prevents our food from spoiling, for the ability to cross 245 – SCIENCE AND TECHNOLOGY – an ocean on a plane within hours, for the calculator, the ATM, and our connection to the Internet Need we go on? The printing press, toothpaste Science- Technology -Science Relationship Technology is applied science science put... the rate of food production increase—at this moment—is not keeping up with the rate of population growth In other words, the amount of mouths to feed is increasing faster than our ability to feed them The uneven distribution of food, rather than the lack of food, however, is causing most of the hunger problems While huge amounts of food are being thrown away in some parts of the world, people in other . Each kind of atom or molecule can gain or lose energy only in particular discrete amounts. When an atom gains energy, light at the wavelength associated with that energy is absorbed. When. with information about the outside world. Animals engage in innate and learned social behavior. These behaviors include hunting or searching for food, nesting, migrating, playing, caring for their young,. a nuclear membrane and it contains genetic infor- mation inscribed along one or more molecules of DNA. The DNA acts as a library of information and a set of instructions for making new cells and cell