How are the subatomic particles arranged in an atom according to modern structure of the atom?

The Bohr's model of the atom is a pivotal concept that revolutionized our understanding of atomic structure. Created by Niels Bohr in 1913, this model was a significant improvement over previous atomic models. Bohr proposed that electrons orbit the nucleus at certain fixed energy levels, without radiating energy. These orbits, or shells, are located at certain distances from the nucleus and serve as the allowed paths for the electrons.

According to this model, an electron can move to a higher energy level by absorbing energy and can move to a lower energy level by emitting energy in the form of light. This concept explained the quantized nature of the atomic emission and absorption spectra. A critical point to note is that Bohr's model works well for the hydrogen atom but is less accurate for other elements with more electrons.

Electron configuration is essentially the 'address book' for the electrons within an atom. It details how electrons are distributed among the various orbitals and energy levels inside the atom. Each electron occupies the lowest energy orbital available, a principle known as the Aufbau principle. This configuration determines how atoms bond and interact with each other.

For example, the electron configuration of carbon is written as 1s² 2s² 2p², reflecting the 'filling order' of electrons. The notation 1s² denotes that the first energy level (n=1) s orbital is fully occupied by two electrons, and so forth. Understanding electron configuration allows chemists to predict the chemical properties of the element and its reactivity in chemical reactions.

The atomic number is a fundamental trait of every element as it uniquely identifies an element. In simpler terms, the atomic number is the count of protons found in the nucleus of an atom. Since protons carry a positive charge, the atomic number also indicates the positive charge of the nucleus.

For instance, carbon has an atomic number of 6, which means it has 6 protons. This is the defining feature of carbon, as another element with 6 protons does not exist. The atomic number also establishes the identity of the element and its location on the periodic table. Importantly, for a neutral atom, the atomic number also equals the number of electrons, which balance the positive charge of the protons with their negative charge.

Subatomic particles are the building blocks of atoms. These particles include protons, neutrons, and electrons. Protons are positively charged and reside in the nucleus, giving an atom much of its mass and defining its atomic number. Neutrons are uncharged particles also found in the nucleus and contribute to an atom's mass. They play a key role in the stability of the nucleus.

Electrons are negatively charged particles and are relatively light compared to protons and neutrons. They move around the nucleus at various energy levels. The interactions between these subatomic particles are fundamental to the chemical properties of elements and form the basis for the chemical behavior of atoms during reactions.