A period on the periodic table is a horizontal row. The atoms in this row show a trend in their width, and in the amount of work needed to make them an ion, among the fe â¦ w other similarities.
A coordinate grid has two perpendicular lines, or axes, labeled like number lines. The horizontal axis is called the x-axis. The vertical axis is called the y-axis. The point where the x-axis and y-axis intersect is called the origin. The numbers on a coordinate grid are used to locate points. Each point can be identified by an ordered pair of numbers; that is, a number on the x-axis called an x-coordinate, and a number on the y-axis called a y-coordinate. Ordered pairs are written in parentheses (x-coordinate, y-coordinate).
To plot a single point on the axis, we start with a coordinate, which is a pair of points each representing a distance travelled on an axis. The x-axis comes first, and then the y-axis. For the point (1,2), the x- coordinate is 1 and the y- coordinate is 2. Any other point is plotted in the exact same manner. The plot below has several points marked, some with missing coordinates.