Answer:
- <em>1. The mass of an atom is concentrated at the nucleus.</em>
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- <em>3. Positive charge is condensed in one location within the atom.</em>
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- <em>4. The majority of the space inside the atom is empty space.</em>
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- <em>6. The atom contains a positively charged nucleus.</em>
Explanation:
When J.J Thmpson discovered the electron, he depicted the atom by the plum pudding model: a solid dough of homogeneously distributed positive charge (the pudding) containing negatively charged electrons (the plums).
Later, the scientist <em>Ernest Rutherford</em>, with its experiment of the gold foil experiment showed that the subatomic particles where not all concentrated in a solid part.
When a thin gold foil was bombarded with alpha particles (positively charged nuclei of helium atoms), most of the particles went through the gold sheet, with little deviation, but some particles bounded with a high deviation.
Such few high deviations were explained by the fact that there was a heavy region in the atom (the core or nucleus) with the positive charge that repelled the positively charged alpha particles.
Thus, <em>the mass of the atom was conentrated at the nucleus</em> (choice 1), where the positive charge is distributed in one location, which is the nucleus (not over the entire atom, just on the nucleus) discarding the choice number 2 (that a positive charge is spread equally over the atom) and proving choices 3 (<em>the positive charge is condensed in one location within the atom</em>) and 6 (<em>the atom contains a positively charged nucleus</em>).
Since most of the particles indeed went through the nucleus, this nucleus has to occupy little space, and most of the atom was empty space, proving choice 4 (<em>the majority of the space inside the atom is empty space</em>).
Answer:
Explanation:
To solve this problem, we must understand the relationship between mass of a substance and the number of atoms.
Atoms are the smallest indivisible particles of any matter. A substance can be made up of several number of atoms in their space.
The mass of any substance is a function of the amount of atoms its contains.
The mass of a substance is related in chemistry to the amount of atoms its contains using the parameter called the number of moles.
A mole is the amount of substance that contains the Avogadro's number of particles. This number is 6.02 x 10²³ particles. The particles here can be protons, neutrons, electrons, atoms e.t.c.
Now,
Number of moles = 
Molar mass of copper = 63.6g/mole
Number of moles = 
= 0.03mole
Since 1 mole of a substance contains 6.02 x 10²³atoms
0.03 mole of copper will contain 0.03 x 6.02 x 10²³atoms
= 1.89 x 10²² atoms
He needs to add 1.89 x 10²² atoms to make 2g of the sample.
Example of solid - solid homogeneous mixture is copper metal - silver metal like coins and alloys.
Homogeneous mixture is a mixture in which one of the substances often changes in form as in a solution of sugar in water. It contains variable proportions. Solution can contain two substances, three substances or more, in a single physical state. The component of a solution that is present in greatest quantity is usually called the solvent and all other components are called solutes.
Potassium is an alkali metal with the chemical symbol K. It has an atomic number of 19, meaning that it has 19 positively charged protons. It also contains 19 electrons, which have a negative charge, and 20 neutrons, which do not hold a charge
Hope this help
