Answer:
The plum-pudding model proposed that an atom is composed of negatively-charged particles floating within a sea of positive charges. This sea of positive charges served to counterbalance the negative charge on the electrons so that the atom remains neutral.
Explanation:
J.J. Thompson from experiments he conducted with the rays produced from a cathode tube to which a high voltage is applied across its two ends, discovered that these rays were negatively charged and had a mass much much smaller than the mass of any known atom. These negatively-charged rays were later called electrons. Since the atom was neutral in charge overall, J.J. Thompson then proposed the plum-pudding model.
The plum-pudding model proposed that an atom is composed of negatively-charged particles floating within a sea of positive charges. This sea of positive charges served to counterbalance the negative charge on the electrons so that the atom remains neutral. The name of this model was chosen because it resembled the English dessert, plum-pudding.
Answer: Some are solid, some are gaseous, a few are liquid. Some are metallic: they have a peculiar lustre; some are coloured (like sulfur) or colourless. Some have a low density; some have a high density. Some are malleable and ductile; some are brittle. Some conduct electricity and heat well; some don’t.
Many metals tend to have structural uses. Nonmetallic elements less so.
Metals tend to have crystal forms featuring close-packed centro-symmetrical structures. Nonmetallic elements tend to have crystal structures featuring more open and directionally packed structures.
Some are especially toxic; some are essential to life; some are both depending on exposure level.
Most are stable; some are less so.
Some elements are highly reactive; some are almost inert (helium, neon, and argon may be completely inert in ambient conditions).
Many metals have basic oxides; quite a few oxides of nonmetallic elements form acids when they are dissolved in water. Some elements can go both ways.
There are many generalisations you can make about metallic and nonmetallic elements, and quite a few exceptions at the margins.
Explanation:
Answer:
7.89 g
Explanation:
Step 1: Write the balanced equation
S₈ + 16 F₂(g) → 8 SF₄
Step 2: Calculate the moles corresponding to 2.34 g of S₈
The molar mass of S₈ is 256.52 g/mol.
Step 3: Calculate the moles of SF₄ produced from 9.12 × 10⁻³ mol of S₈
The molar ratio of S₈ to SF₄ is 1:8. The moles of SF₄ produced are 8/1 × 9.12 × 10⁻³ mol = 0.0730 mol
Step 4: Calculate the mass corresponding to 0.0730 moles of SF₄
The molar mass of SF₄ is 108.07 g/mol.
