Science

• is a reaction wherein a heavy nucleus is bombarded by neutrons and thus becomes unstable, which causes it to decompose into two nuclei with equivalent size and magnitude, with a great detachment of energy and the emission of two or three neutrons.

  Nuclear Fission
• It is a nuclear process, where energy is produced by smashing together light atoms. It is the opposite reaction to fission, where heavy isotopes are split apart. Fusion is the process by which the sun and other stars generate light and heat.

  Nuclear fussion
• The smallest unit of matter that can exist independently is an atom.
• Atoms consist of protons, electrons, and neutrons.
• Protons have a positive charge (+1), while electrons have a negative charge (-1). Neutrons do not carry any electrical charge.
• An element is defined as a substance made up of only one type of atom.
• An atom's mass number represents its total number of protons and neutrons, while its atomic number indicates how many protons it has.
• Compounds contain different types of atoms bonded together.
• Isotopes are different forms of elements that contain the same number of protons but varying numbers of neutrons.
• A compound is formed when two or more elements chemically combine.
• Matter refers to anything that has mass and takes up space.
• states that as nations transition from the beginning stages of industrialization to highly industrialized nations, the same societal patterns will emerge, eventually creating a global culture.

  Convergence theory
• A tectonic boundary where two plates are moving toward each other. If the two plates are of equal density, they usually push up against each other, forming a mountain chain. If they are of unequal density, one plate usually sinks beneath the other in a subduction zone.

  Convergent plate
• The ____is everything we can see and study directly. The thinnest layer of the Earth, the ____ still measures about 40 km on average, ranging from 5–70 km (~33-44 miles) in depth. But at the scale of the planet, that’s less than the skin of an apple.

  crust
• There are two types of crust:

  Continental crust and oceanic crust
• (______) can be found at the bottom of the oceans or below the continental crust; it is generally harder and deeper, consisting of denser rocks like basalt

  Oceanic crust
• (_____) contains granite-type rocks and sediments. The _____ crust thicker on land.

  Continental crust
• The ______ extends down 2,890 km, making it the thickest layer of Earth. It makes up about 84% of Earth’s volume.

  Mantle
• The temperatures and pressures of the ____ core are absolutely extreme, at approximately 5,400 °C (9,800 °F) and 330 to 360 gigapascals (3,300,000 to 3,600,000 atm).

  inner core
• The _____ core is a low viscosity fluid (about ten times the viscosity of liquid metals at the surface) – “liquid” is a rather improper term. Because it has a very low viscosity, it is easily deformed and malleable. It is the site of violent convection. It is also thought to suffer very violent convection currents – hey, and guess what? The churning of the ____ core and its relative movement is responsible for the Earth’s magnetic field.

  Outer core
• How old is the universe???

  13.8 billion years
• (Blank theory)proposed that all matter was composed of atoms, indivisible and indestructible building blocks. While all atoms of an element were identical, different elements had atoms of differing size and mass.

  Dalton’s Atomic Theory
• Which planet are gigantic???

  Jupiter
• A gas giant is a large planet composed mostly of gases, such as hydrogen and helium, with a relatively small ​rocky​ core. The gas giants of our solar system are ​?

  Jupiter​, ​Saturn​, Uranus​ and ​Neptune​.
• The basic element in geometrical optics is the ______, a hypothetical construct that indicates the direction of the propagation of light at any point in space. The origin of this concept dates back to early speculations regarding the nature of light.

  Light ray
• If a linear object attached to an oscillator bobs back and forth within the water, it becomes a source of ​straight​ ​waves​. These straight waves have alternating crests and troughs.

  Reflection of waves
• Regardless of the angle at which the wavefronts approach the barrier, one general law of reflection holds true: the waves will always reflect in such a way that the angle at which they approach the barrier equals the angle at which they reflect off the barrier. This is known as the?

  Law of reflection
• Reflection involves a change in direction of waves when they bounce off a barrier. ​Refraction​ of waves involves a change in the direction of waves as they pass from one medium to another. Refraction, or the bending of the path of the waves, is accompanied by a change in speed and wavelength of the waves. It was mentioned that the speed of a wave is dependent upon the properties of the medium through which the waves travel.


  Refraction of waves
• ______

  of water waves is observed in a harbor as Reflection involves a change in direction of waves when they bounce off a barrier; refraction of waves involves a change in the direction of waves as they pass from one medium to another; and ​diffraction​ involves a change in direction of waves as they pass through an opening or around a barrier in their path. Water waves have the ability to travel around corners, around obstacles and through openings. This ability is most obvious for water waves with longer wavelengths.


  Diffraction of waves
• _____, ______, and ______ are all boundary behaviors of waves associated with the bending of the path of a wave. The bending of the path is an observable behavior when the medium is a two- or three-dimensional

  Reflection​, ​refraction​ and ​diffraction​
• Albert Einstein, in his theory of special relativity, determined that the laws of physics are the same for all non-accelerating observers, and he showed that the speed of light within a vacuum is the same no matter the speed at which an observer travels.

  Relativity Theory
• The concept of time dilation states that if two clocks are moving relative to each other, then the clock that appears to be traveling faster will appear to run slower than the clock that appears to be stationary.
• With the exception of hydrogen, the elements on the left-hand side of the periodic table are metals
• Hydrogen acts as a metal in its solid state, but the element is a gas at ordinary temperatures and pressures and does not display metallic character under these conditions
• Metal properties


  • Metallic luster
  • High electrical and thermal conductivity
  • Usually hard solids (mercury is liquid)
  • Usually ductile (capable of being drawn into a wire) and malleable (capable of being hammered into thin sheets)
  • Most have high melting points
  • Readily lose electrons (low electron affinity)
  • Low ionization energies
• Metals


  Elements on the left-hand side of the periodic table
• The two rows of elements below the body of the periodic table are metals. Specifically, they are a collection of transition metals that are called​ ​the lanthanides and actinides​ or the rare earth metals. These elements are located below the table because there wasn't a practical way to insert them into the transition metal section without making the table look.


  lanthanides and actinides​
• There is a zig-zag line toward the right side of the periodic table that acts as a sort of border between metals and nonmetals. Elements on either side of this line exhibit some properties of metals and some of the nonmetals. These elements are the​ ​metalloids​, also called semimetals. Metalloids have variable properties, but often:

  ● metalloids have multiple forms or allotropes

  ● can be made to conduct electricity under special conditions (semiconductors)

  Metalloids (or Semimetals)
• The elements on the right-hand side of the periodic table are the​ ​nonmetals​. Nonmetals properties are:

  ● usually poor conductors of heat and electricity

  ● often liquids or gases at room temperature and pressure

  ● lack metallic luster

  ● readily gain electrons (high electron affinity)

  ● high ionization energy

  Nonmetals
• Groups are the columns of the table. Atoms of elements within a group have the same number of valence electrons. These elements share many similar properties and tend to act the same way as each other in chemical reactions.

  Element groups