36 terms

Chemistry I Unit 2 Vocabulary

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matter
material that has mass and takes up space. Matter is made up of atoms. Matter has four states 1.gas 2. liquid 3. solid 4. plasma determined by particle arrangement, particle energy, and particle distance.
mass
the amount of matter, measured in units of grams or kilograms (SI). It is a measure of the tendency of an object to resist acceleration.
density
A physical property of matter: a property of a substance that describes how much mass the substance contains per unit of volume: typical units are grams per cubic centimeter (g/cm3). Saying "the density of mercury is 13.55g/cm3" is the same as saying "the mass of 1 cm3 of mercury is 13.55g". Mass divided by volume gives you density.
volume
an amount of space having length, width, and height that an object takes up. The SI unit of volume is the cubic meter (m3)
solid
Solids are made of densely packed atoms. A relatively dense, rigid state of matter, with a definite volume and shape. Particles in solids are held by intermolecular forces( bonds between molecules) Molecules in solids are often packed close together in regularly repeating patterns, and vibrate around fixed positions.
liquid
A state of matter that has a high density and is incompressible compared to gas.The particles are tightly packed, but far enough apart to slide over one another (intermolecular forces have weakened) Liquids have an indefinite shape and a definite volume. Liquids take the shape of their container but do not expand to fill the container as gases do.
gas
Matter in a form that has low density, is easily compressible and expandable, and expands spontaneously when placed in a larger container. Its atoms are very far apart and move freely (intermolecular forces have been completely broken). They have indefinite shape and an indefinite volume.
plasma
It's a gaslike state of matter consisting of positively charged ions, free electrons, and neutral particles. A hot, energetic phase of matter in which the atoms are broken apart into positive ions and negative electrons that move independently of each other. Plasma, like gases, have an indefinite shape and an indefinite volume. They are good conductors of electricity. It is the most common state of matter in the universe. Plasma is found in stars, the sun, the solar wind, lightening, and fire.
malleable
A physical property of matter: a substance that can be hammered, rolled or pressed (undergo compression stress) into thin sheets without cracking. metals are typically malleable materials. Malleability relates to how readily a material shape can be changed.
ductile
a property of materials that describes ease of stretching or molding and lack of brittleness. Capable of being drawn into wire (undergo tensile stress) without breaking. Metals are typically ductile materials. ductility = capacity of a material to deform permanently rather then fracture in response to stress.
elastic
a physical property of a material where the material returns to its original shape after being deformed, unlike ductile or malleable. A elastic collision is one in which the total kinetic energy of the colliding bodies or particles is the same after the collision as it was before as in the collision of atoms.
conductivity
A measure of how easily an electric current can pass through a material. the conductivity is the reciprocal of the resistance. The SI unit of conductance is the siemens
viscosity
The viscosity of a fluid is a measure of its resistance to flow or to gradual deformation under an applied force (shear stress or tensile stress). It is a property arising from friction between neighboring particles in a fluid that are moving at different velocities. Low viscosity is thin like water versus high viscosity as thick like honey.
atom
the smallest particle of an element that retains the chemical properties of the element. It is the basis of chemistry. Atoms are electrically neutral, with a positively charged nucleus that binds one or more electrons in motion around it. It has 3 parts: proton , neutron, electron. They are mostly empty space.
proton
a tiny particle in the nucleus that has a positive electrical charge. The number of protons determine the atomic number.
neutron
Neutron is one of the three smaller particles that make up the atom. They are in the nucleus and have no electrical charge. Atomic mass - atomic number = # of neutrons. All atoms of the same element have the same number of protons in the nucleus but they don't necessarily have the same number of neutrons. (when have different numbers of neutrons the variations are called isotopes)
electron
a tiny negatively charged particle that fills the outer shell or orbit of an atom as it orbits the nucleus. It is the smallest of the three particles that make up an atom as its mass is almost 1,00 times smaller than the mass of protons. Electrons live in something called energy levels or shells and only so many can be in any certain shell. They move quickly. And is responsible for chemical bonds. In a neutral atom, the atomic number gives you the number of electrons as well as protons. Most of the properties of atoms are determined by their electrons. The number of spectral lines is related to the number of electrons in each atom.
ion
an atom or small molecule with an overall positive or negative charge as a result of an imbalance of protons and electrons. Since the number of proton doesn't change, it is fewer or extra electrons that create an ion.
Bohr
In 1913, Bohr, a student of Rutherford's developed a new model of the atom. He proposes that electrons are arranged in concentric circular orbits around the nucleus. Also known as planetary model because modeled after solar system. Summarized by 4 principles. 1. electrons occupy only certain orbits around the nucleus. Those orbits are stable and are called stationary orbits. 2. Each orbit has an energy associated with it. The orbit nearest the nucleus has an energy of E1, the next E2 etc. 3. Energy is absorbed when an electron jumps from a lower orbit to a higher one and energy is emitted when an electron falls from a higher orbit to a lower one. 4. The energy and frequency of light emitted or absorbed can be calculated by using the difference between the two orbital energies.
Rutherford
Ernest Rutherford (1910) discovered the existence of the nucleus in an atom through his gold foil experiment and alpha particles sent through the foil. (these particles are positively charged)
Dalton
Architect of first modern atomic theory. He stated 4 postulates based on what little evidence there was at the time but remain true today: 1. All elements are made of tiny indivisible particles called atoms. 2.All atoms of the same element are alike but different from atoms of every other element. 3. Chemical reactions rearrange atoms but do not create, destroy, or convert atoms from one element to another. 4. Compounds are made from combining atoms in simple whole number ratios. He also wrote Dalton's law of partial pressures: law that states that the total pressure exerted in a mixture of gasses is the sum of the partial pressures of each individual gas in the mixture. For example, if dry oxygen gas at 713 torr is saturated with water vapor at 25 torr, the pressure of wet gas is 738 torr.
A.M.U.
atomic mass unit: a unit of mass equal to 1/12 the mass of carbon-12 nucleus;1.661 x 10-21 kg.
Valence electron
electrons in the highest unfilled energy level (outer most shell) of any element that are responsible for making chemical bonds
Quantum theory
a theory of physics and chemistry that accurately describes the universe on very small scales, such as the inside of an atom. It says that an electron can be found anywhere around the nucleus.
Anion
a negatively charged ion. They have extra electrons to create the negative charge. Nonmetals are typically anions.
Cation
a positively charged ion. They have fewer electrons to create the positive charge. Metals typically form cations.
Isotope
atoms or elements that have the same number of protons in the nucleus but different number of neutrons. The average atomic mass of an element is the weighted average of all the atomic masses of all the isotopes of an element.
Radioactive
spontaneous emission of particles or high-energy electromagnetic radiation from the nuclei of unstable atoms. It is when an atomic nucleus decays. In radioactive decay, neutrons are knocked out of the nucleus.
Schrodinger
In 1926 Erwin Schrödinger, an Austrian physicist, took the Bohr atom model one step further. Schrödinger used mathematical equations to describe the likelihood of finding an electron in a certain position. This atomic model is known as the quantum mechanical model of the atom. Unlike the Bohr model, the quantum mechanical model does not define the exact path of an electron, but rather, predicts the odds of the location of the electron. This model can be portrayed as a nucleus surrounded by an electron cloud. Where the cloud is most dense, the probability of finding the electron is greatest, and conversely, the electron is less likely to be in a less dense area of the cloud. Thus, this model introduced the concept of sub-energy levels.
Bohr Model
Shows all the particles in the atom. In the nucleus are circles. Each circle represents a single neutron or proton. Protons should have a + sign or P written on them. Neutrons should be blank or have an N. In a circle around the nucleus are the electrons. Electrons should have a - sign or an e.
Lewis Dot Structure
Different from the Bohr atom model because it only shows the element symbol and it's outer most electron shell.
nucleus
the central part of an atom.
element
when only one kind of atoms combine. Every element is unique and as an atomic number. Hydrogen is the only element without neutrons.
molecule
when two or more atoms combine it's called a molecule
compound
when atoms combine that are different it's a compound
atomic number
also called proton number. Tells you the number of protons in the atom.