The Montgomery County school board's vote to close Francis Scott Key Junior High School was the result of a "trade-off" by two board members that will separate students along racial and economic lines, parents from the area charged last week.

Key, located in Silver Spring just north of the Beltway, is one of the most evenly and successfully integrated schools in the county, according to white and minority parents whose children attend the school. But with its closing the bulk of its white students will be reassigned to a school farther north of the beltway in a neighborhood of modest integration, while many minority students will be sent to a school south of the beltway in East Silver Spring.

"What is happening is racial," says Ruth West, whose daughter is the only black child in her class in a program for the gifted and talented at Key. "As a minority parent that is the only way I can see it."

West and other parents interviewed charged that board member Marian L. Greenblatt had agreed to close one school in her neighborhood, Key, in order to protect another, Cresthaven Elementary. Similarly, the parents said, board president Carol F. Wallace had agreed to keep Cresthaven open if a school in her area, White Oak Junior High, was spared.

The closing was approved on a 3-2 vote, with one board member abstaining. Greenblatt, Wallace and board member Suzanne Peyser voted in favor of closing Key.

Greenblatt and Wallace denied that there was any "trade-off" and said that White Oak Junior High deserved to stay open because it is in a better location than Key and has access to more facilities for extracurricular activities.

"It is no trade-off," Wallace said. "There is a very valid argument. White Oak is centrally located. And you need to keep Cresthaven open because it is on the southern tier of schools feeding into Springbrook High School . You have to have balance in the cluster."

Board member Blair Ewing, who abstained from the vote on the Key closing, said he did so because the problem of racial balance was not taken into consideration. He said, however, that he believes Key needs to be closed and that he would have voted to close it if the board had made boundary changes that would have restored some integration patterns.

"There are arguments on both sides of the question," Greenblatt said as the board prepared to vote on Key late Wednesday night. But she said compromises must be made in dealing with the controversial problems of school closings, and that a neighborhood should not have to forfeit more than one school. It was this remark, in part, that fueled suspicions among parents that "Key was given away" as part of deal between Greenblatt and Wallace.

The underlying motive for the vote, parents charged, was to ensure that schools north of the beltway along New Hampshire Avenue remain insulated from lower-income and minority students who reside inside the beltway. By preserving White Oak Junior High instead of Key, the parents said, the predominantly white student population north of the beltway would be guaranteed enrollment at Springbrook High School, which is less than 30 percent minority.

One white parent said board members were responding to "a nebulous fear" among some parents that, if Key stayed open, children who attended it would wind up at Blair High School, which has the largest minority poulation of any high school in the county.

"Basically it is the old 'them and us' mentality," said the parent, who asked not to be identified. "What I hate to see is the leaders preying on that fear. What is missing in this debate over Key is that the school is a romping stomping success. It is a heterogeneous success."

With the closing of Key in 1983, the majority of the school's white students will be reassigned to White Oak and Banneker junior high schools and will go on to Springbrook High.

Most of Key's minority students, however, who make up 46 percent of the student population, will enroll at Eastern Junior High south of the beltway and then Blair High School.