Which scientist was the first to propose that atomic structure contains electrons?

Can somebody plz help answer these questions correctly (only if u know the answer) thanks! :3

ss7ja [257]

1. Reduce, reuse, and recycle

Conserve water

plant a tree

2. An environmentally aware business considers more than just profits — it considers its impact on society and the environment. Such a business is sustainable because it contributes to the health of the structure within which it operates, thereby helping construct an environment in which the business can thrive.

3. Aboriginal people are rich in environmental knowledge and can provide important perspectives when considering the impact of economic decisions on the environment. Aboriginal people are also a source of sustainability strategies that can contribute to our collective well-being.

:D

3 0

3 years ago

For the transmutation shown, which of the following is X?

Vladimir79 [104]

Answer:

Choice A: carbon-12, $^{12}_{\phantom{0}6}\text{C}$ .

Explanation:

The number on the top-left corner of each particle is its mass number.
The number on the lower-left corner of each particle is its atomic number.

Let

the mass number of X be A, and
the atomic number (a.k.a. proton number) of X be Z.

Symbol of X: $^{A}_{Z}\text{X}$ .

Consider the two conservation laws:

Sum of mass numbers on the left-hand side = Sum of mass numbers on the right-hand side.
Sum of atomic numbers on the right-hand side = Sum of atomic numbers on the right-hand side.

Sum of mass numbers:

Left-hand side: 9 + 4;
Right-hand side: A + 1.

Equate the two sides:

$9 + 4 = A + 1$

$A = 12$ .

Thus the mass number of X is 12.

Try the steps above to find the atomic number of X. The number $0$ on the lower-left corner of $^{1}_{0}n$ indicates that the atomic number of this neutron is zero.

$Z = 6$ .

Thus the atomic number of X is 6.

What element is X? Refer to a modern periodic table. The element with atomic number 6 is carbon. The symbol for carbon is $C$ . The mass number of this isotope is 12. The answer will be $^{12}_{\phantom{0}6}\text{C}$ .