Modern atomic theory states that atoms are neutral. how is this neutrality achieved?

Due to interaction of proton particle and electron particle, neutrality in atom is achieved.

It is a common known statement that matter is composed of atom, and atom is composed of particles called as electron, neutron, and proton. The atoms are considered as charged particles due to the presence of charges on its composition molecules.

The electrons are negative charged particles whereas the protons are positively charged particles. The number of protons and electron in an atom remains equal. Due to this condition, all the protons react with the entire electron leading to a condition called neutrality.  

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation: