英译汉1,An atom consists of a very small positively charged nuc

英译汉
1,An atom consists of a very small positively charged nucleus,surrounded by negative
electrons held by electrostatic attraction.The motion of electrons changes when chemical
bonds are formed,nuclei being unaltered.
2,Electronegativity is the power of an atom to attract electrons to itself in a chemical bond.
Different numerical estimates agree on qualitative trends:electronegativity increases from
left to right along a periodic table.Elements of low electronegativity are called
electropositive.Electropositive elements form metallic solids.Electronegative elements
form molecules or polymeric solid with covalent bonds.
3,Molecular orbitals are wavefunctions for electrons in molecules,often formed by the
linear combination of atomic orbitals approximation.Overlappling atomic arbitals can give
bonding and antibonding molecular orbitals.Electrons in bonding molecular orbitals have
an increased probability of being in the region between the nuclei.
4,Aromatic rings are made up of six sp2
hybridized carbons.Each carbon forms three σ
bonds which results in a planar ring.The remaining 2p orbital on each carbon is
perpendicular to the plane and can overlap with a neighboring 2p orbital on either side.This
means that a molecular orbital is formed round the whole ring such that the six π electrons
are delocalized around the ring.This results in increased stability such that aromatic rings are less reactive than alkenes.
5,Optical isomers are configurational isomers which have the ability to rotate
plane-polarized light clockwise or counterclockwise.They have identical chemical and
physical properties (apart from their effects on plane-polarized light),but can have different
biological properties.
6,Nucleophilic substitutions are reactions which involve the substitution of one nucleophile
for another nucleophile.Alkyl halides,carboxylic acid,and carboxylic acid derivatives
undergo nucleophilic substitution,but the mechanisms for alkyl halides are quite different
from those of carboxylic acid and carboxylic acid derivatives.
7,The energy of an isolated system is constant.An alternative equivalent expression is that
energy may be neither created nor destroyed,although the energy within a system may
change its form.It is a result of the first law that energy in an open system may be
exchanged with the surroundings as either work or heat but may not be lost or gained in any
other manner.
8,The number of each type of amino acid in a protein can be determined by acid hydrolysis
and separation of the individual amino acids by ion exchange chromatography.The amino
acids are detected by colarimetric reaction with,for example ninhydrin.

太多了啊,第一个是 原子由极小的带正电荷组成,带正电的核被带负点的电子环绕.电子的运动规律改变当化学键形成时,但是正电荷属性不变.
就是这样,后面的不说了,太多了不好意思哈