AP化学词汇（三）

　　对于中国学生来说，一门优秀的AP成绩不仅对学生的申请有所帮助，还能为以后融入美国的学习生活打下基础。对于学习AP的同学来说，掌握词汇是至关重要的，词汇量不足将对答题速度和对标题理解都会影响。新东方在线AP盘点了各科目的词汇，今天为大家带来的是：AP化学词汇(三)，建议同学们收藏。

　　AP化学词汇(三)

　　Periodic Table of

　　the Elements

　　元素周期表

　　The periodic table is a tabular arrangement of the chemical elements,ordered by their atomic number (number of protons), electron configurations, and recurring chemical properties. This ordering shows periodic trends, such as elements with similar behavior in the same column.

　　It also shows four rectangular blocks with some approximately similar chemical properties.

　　atomic symbols

　　元字符号

　　Atomic symbol, sometimes called a chemical symbol, is a one to three letter code for chemical elements.

　　formula

　　方程式

　　A mathematical relationship or rule expressed in symbols.

　　ion

　　离子

　　An atom or molecule with a net electric charge due to the loss or gain of one or more electrons.

　　isotope

　　同位素

　　Isotopes are variants of a particular chemical element which differ in neutron number, although all isotopes of a given element have the same number of protons in each atom. The term isotope is formed from the Greek roots isos and topos, meaning "the same place"; thus, the meaning behind the name is that different isotopes of a single element occupy the same position on the periodic table.

　　subscript

　　下标

　　(of a letter, figure, or symbol) Written or printed below the line.

　　atomic number

　　原子序数

　　In chemistry and physics, the atomic number of a chemical element (also known as its proton number) is the number of protons found in the nucleus

　　of an atom of that element, and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic

　　number uniquely identifies a chemical element.

　　weighted averages

　　of the masses

　　平均质量

　　To find the AVERAGE ATOMIC MASS of an atom, we take into account all of the isotopes that exist and the percentage of each type. The calculation

　　of the average atomic mass is a WEIGHTED AVERAGE. Average atomic mass = Σ (mass of isotope × relative abundance)

　　main group

　　主族

　　In chemistry and atomic physics, the main group is the group of elements whose lightest members are represented by helium, lithium, beryllium,boron, carbon, nitrogen, oxygen, fluorine, and neon as arranged in the periodic table of the elements. The main group includes the elements (except hydrogen) in groups 1 and 2 (s-block), and groups 13 to 18 (p-block).

　　atomic radius

　　原子半径

　　The atomic radius of a chemical element is a measure of the size of its atoms, usually the mean or typical distance from the center of the nucleus to

　　the boundary of the surrounding cloud of electrons. Since the boundary is not a well-defined physical entity, there are various non-equivalent definitions of atomic radius.

　　nuclear charge

　　核电核力

　　The nuclear charge is the total charge of all the protons in the nucleus. It has the same value as the atomic number.

　　effective nuclear

　　charge

　　有效核电荷数

　　The effective nuclear charge is the net positive charge experienced by an electron in a multi-electron atom. The term "effective" is used because the

　　shielding effect of negatively charged electrons prevents higher orbital electrons from experiencing the full nuclear charge of the nucleus due to the repelling effect of inner-layer electrons.

　　electronegativity

　　电负性

　　Electronegativity, symbol χ, is a chemical property that describes the tendency of an atom or a functional group to attract electrons (or electron

　　density) towards itself. An atom's electronegativity is affected by both its atomic number and the distance at which its valence electrons reside from the charged nucleus.

　　affinity

　　亲和性

　　In chemical physics and physical chemistry, chemical affinity is the electronic property by which dissimilar chemical species are capable of forming chemical compounds.

　　non-metal

　　非金属

　　In chemistry, a non-metal (or non-metal) is a chemical element that mostly lacks metallic attributes. Physically, non-metals tend to have relatively low melting and boiling points, and densities, are mostly brittle if solid, and are usually poor conductors of heat and electricity; chemically, they tend to have relatively high ionization energy, electron affinity, and electronegativity values, and gain or share electrons when they react with other elements or compounds. Seventeen elements are generally classified as non-metals; most are gases (hydrogen, helium, nitrogen, oxygen, fluorine, neon, chlorine, argon, krypton, xenon and radon); one is a liquid (bromine), and a few are solids (carbon, phosphorus, sulfur, selenium, and iodine). Metalloids such as boron, silicon and germanium are sometimes counted as non-metals.

　　metal

　　金属

　　A metal (from Greek μέταλλον métallon, "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, has a lustrous appearance, and conducts both electricity and heat relatively well. Metals are typically malleable (they can be hammered into thin sheets) or ductile (can be drawn into wires). A metal may be a pure chemical element such as gold, or an alloy of variable composition such as stainless steel, or an alloy of fixed composition, otherwise known as an intermetallic compound, such as one of the nickel aluminides, Ni3Al, NiAl, or NiAl3. Most elemental metals are denser than other elements; iron, for example, is heavier than carbon, and sulfur.

　　boiling points

　　沸点

　　The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding environmental pressure. A liquid in a partial vacuum has a lower boiling point than when that liquid is at atmospheric pressure.

　　group

　　族

　　In chemistry, a group is a vertical column in the Periodic Table. Groups may be referred to either by number or by name. For example, Group 1 is also known as the Alkali Metals.

　　valence electrons

　　价电子

　　In chemistry, a valence electron is an electron that is associated with an atom, and that can participate in the formation of a chemical bond; in a

　　single covalent bond, both atoms in the bond contribute one valence electron in order to form a shared pair.

　　third ionization

　　energy

　　第三电离能

　　The third ionization energy is the energy required to form 3+ cations: M 2+ (g) → M 3+ (g) + e-and so on. Ionization energies are always positive numbers, because energy must be supplied (an endothermic energy change) to separate electrons from atoms.

　　quantum number

　　量子数

　　Quantum numbers describe values of conserved quantities in the dynamics of a quantum system. In the case of quantum numbers of electrons, they can be defined as "the sets of numerical values which give acceptable solutions to the Schrödinger wave equation for the hydrogen atom".

　　principal quantum

　　number

　　主量子数

　　In quantum mechanics, the principal quantum number (symbolized n) is one of four quantum numbers which are assigned to each electron in an atom to

　　describe that electron's state. As a discrete variable, the principal quantum number is always an integer. As n increases, the number of electronic shells increases and the electron spends more time farther from the nucleus.

　　angular momentum

　　quantum number

　　角量子数

　　A quantum number for an atomic orbital that determines its orbital angular momentum and describes the shape of the orbital. Also known as the

　　azimuthal quantum number.

　　sublevel

　　亚层

　　A sublevel is an energy level defined by quantum theory. In chemistry,sublevels refer to energies associated with electrons. In physics, sublevels

　　may also refer to energies associated with the nucleus.

　　magnetic quantum

　　number

　　磁量子数

　　In atomic physics, the magnetic quantum number is the third of a set of quantum numbers (the principal quantum number, the azimuthal quantum

　　number, the magnetic quantum number, and the spin quantum number) which describe the unique quantum state of an electron and is designated by the letter m. The magnetic quantum number denotes the energy levels available within a subshell.

　　spin quantum

　　number

　　自旋量子数

　　In atomic physics, the spin quantum number is a quantum number that parameterizes the intrinsic angular momentum (or spin angular momentum, or simply spin) of a given particle.

　　physical properties

　　物理性质

　　A physical property is any property that is measurable, whose value describes a state of a physical system. The changes in the physical properties of a system can be used to describe its transformations or evolutions between its momentary states. Physical properties are often referred to as observables.

　　They are not modal properties. Quantifiable physical property is called physical quantity.

　　energy level

　　能级

　　A quantum mechanical system or particle that is bound—that is, confined spatially—can only take on certain discrete values of energy. This contrasts with classical particles, which can have any energy. These discrete values are called energy levels.

　　Democritus

　　德谟克利特

　　(c.460–c.370 bc) Greek philosopher. He developed the atomic theory originated by his teacher, Leucippus, which explained natural phenomena in terms of the arrangement and rearrangement of atoms moving in a void.

　　atom

　　原子

　　An atom is the smallest constituent unit of ordinary matter that has the properties of a chemical element. Every solid, liquid, gas, and plasma is

　　composed of neutral or ionized atoms. Atoms are extremely small; typical sizes are around 100 picometers. Atoms are small enough that attempting to predict their behavior using classical physics – as if they were billiard balls,for example – gives noticeably incorrect predictions due to quantum effects.

　　atomic theory

　　原子理论

　　In chemistry and physics, atomic theory is a scientific theory of the nature of matter, which states that matter is composed of discrete units called atoms. It began as a philosophical concept in ancient Greece and entered the scientific mainstream in the early 19th century when discoveries in the field of chemistry showed that matter did indeed behave as if it were made up of atoms.

　　plum pudding

　　model

　　枣糕模型

　　The plum pudding model was a model of the atom that incorporated the recently discovered electron, and was proposed by J. J. Thomson in 1904. Thomson had discovered the electron in 1897.

　　Solar System model

　　原子太阳系模型

　　An analogy often used in chemistry to describe the atom as “the solar system”, but not everyone agrees on its helpfulness.

　　chemical reactions

　　化学反应

　　A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical

　　equation.

　　John Dalton

　　约翰·道尔顿

　　John Dalton FRS (/ˈdɔːltən/; 6 September 1766 – 27 July 1844) was an English chemist, physicist, and meteorologist. He is best known for Periodic introducing the atomic theory into chemistry, and for his research into colorintroducing the atomic theory into chemistry, and for his research into color blindness, sometimes referred to as Daltonism in his honor.

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