The nuclear atom
International Baccalaureate · IB Diploma · Chemistry · HL Topic 2 3:51 English narration · English + 中文 subtitles burned in
Chapters
Transcript
A salt crystal conducts when dissolved but not when solid.
盐晶体溶解时导电，但固态时不导电。
The ions exist in both states; their ability to move changes.
离子在两种状态下都存在，但其移动能力发生了变化。
Ionic bonding is electrostatic attraction between oppositely charged ions.
离子键是带相反电荷的离子之间的静电吸引。
A covalent bond involves shared electrons.
共价键涉及共享电子。
Metallic bonding involves attraction between positive metal ions and delocalized electrons.
金属键涉及正金属离子与离域电子之间的吸引。
Ionic bond: Attraction between oppositely charged ions.
离子键：带相反电荷的离子之间的吸引。
Delocalized electron: An electron not confined to one atom or bond.
离域电子：未局限于单个原子或化学键中的电子。
To explain a bulk property, name the structure, particles, forces, and mobile charge carriers.
为了解释宏观性质，请列出结构、粒子、作用力及可移动电荷载体。
Simple molecular substances can have strong covalent bonds inside molecules but weak attractions between molecules.
简单分子物质内部可能存在强共价键，但分子间仅存在弱吸引力。
In the lab: Compare substances using evidence such as melting point, conductivity when solid and molten, and solubility.
在实验室中，利用熔点、固态和熔融态下的导电性以及溶解度等证据来比较物质。
One property rarely proves a structure; use a pattern of evidence.
单一性质很难证明结构，应使用证据模式进行判断。
Known: an element has atomic number 12 and mass number 24.
已知：某元素的原子序数为12，质量数为24。
Protons equals 12.
质子数等于12。
Neutrons equals mass number minus atomic number, which is 24 minus 12, equaling 12.
中子数等于质量数减去原子序数，即24减12，等于12。
A 2 plus ion has electrons equal to 12 minus 2, which is 10.
带2+电荷的离子，其电子数等于12减2，即10。
Charge changes electron count, not the nucleus.
电荷改变的是电子数，而非原子核。
Your turn: An atom has atomic number 17 and mass number 35.
课堂练习：某原子的原子序数为17，质量数为35。
Find its number of neutrons.
求其中子数。
Melting a simple molecular substance usually overcomes intermolecular attractions; it does not require breaking all covalent bonds within each molecule.
熔化简单分子物质通常只需克服分子间作用力，而无需破坏每个分子内部的所有共价键。
Not true: All covalent substances have low melting points.
不正确。 并非所有共价物质都具有低熔点。
Giant covalent substances such as diamond and silicon dioxide have very high melting points because covalent bonds must be broken throughout the structure.
像金刚石和二氧化硅这样的大共价结构具有非常高的熔点，因为必须破坏整个结构中的共价键。
Low melting points belong to simple molecular substances, where only intermolecular attractions are overcome.
低熔点属于简单分子物质，其中仅需克服分子间作用力。
Ionic bonding is electrostatic attraction between oppositely charged ions.
离子键是带相反电荷的离子之间的静电吸引力。
To explain a bulk property, name the structure, particles, forces and mobile charge carriers.
要解释宏观性质，需指出结构、粒子、作用力以及可移动的电荷载体。
Watch for: melting a simple molecular substance usually overcomes intermolecular attractions; it does not require breaking all covalent bonds within each molecule.
注意：熔化简单的分子物质通常只需克服分子间引力；不需要破坏每个分子内的所有共价键。
An atom has atomic number 19 and mass number 39.
某原子的原子序数为19，质量数为39。
Find the neutron count and the electron count in the 1 plus ion.
求该+1离子中的中子数和电子数。
The charge does not change the nucleus.
电荷不会改变原子核。
The result is 20 neutrons, and 18 electrons in the 1+ ion.
结果是20个中子；1+离子中有18个电子。
In an ionic lattice every positive ion is next to negative ions and every negative ion next to positive ones.
在离子晶格中，每个正离子旁边都是负离子，每个负离子旁边都是正离子。
The attraction acts in all directions through the whole lattice.
这种吸引力在整个晶格中向各个方向起作用。
An atom has atomic number 12 and mass number 25, and forms a 2 plus ion.
某原子的原子序数 Z 为 12，质量数 A 为 25，并形成带 2 个正电荷的离子。
State the protons, neutrons and electrons before and after ion formation.
请写出该原子形成离子前后的质子数、中子数和电子数。
What changes in an isotope instead?
相比之下，同位素之间变化的是什么？
The atom has 12 protons and 13 neutrons; it has 12 electrons, then 10 in the ion.
十二个质子，十三个中子；电子数由十二变为十。
Ion formation changes electrons.
离子形成会改变电子数。
An isotope has the same atomic number but a different neutron count; it need not have a different charge.
同位素具有相同的Z但中子数不同；其电荷不一定不同。
Retrieve the technical meanings, then vary one input in the original transfer and justify the model condition.
请回顾相关技术术语的含义，然后在原始迁移中改变一个输入变量，并为模型条件提供依据。