Pull one electron out of a neutral volume and the ledger tips by +e, the elementary charge. Such tiny local imbalances are exactly what produce the electric fields that steer plasma motion. The clean +e result assumes an otherwise exactly neutral background and ignores the smeared-out cloud of neighboring charges.
A count imbalance fixes the sign of the net charge. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
One missing electron leaves positive charge
The ion count stays 4, but the electron count drops to 3.
4(1)+3(−1)=1C
The sign tells which charge is in excess
The net charge is positive 1 coulomb because ion charge exceeds electron charge.